In my reproduction, I could find a Groovy script <project directory>/Libs/TempTestSuitexxxxxxxxxxx.groovy of which size is 1,229,051 bytes. Its content is like this:
import com.kms.katalon.core.logging.KeywordLogger
import com.kms.katalon.core.exception.StepFailedException
import com.kms.katalon.core.reporting.ReportUtil
import com.kms.katalon.core.main.TestCaseMain
import com.kms.katalon.core.testdata.TestDataColumn
import com.kms.katalon.core.testcase.TestCaseBinding
import com.kms.katalon.core.driver.internal.DriverCleanerCollector
import com.kms.katalon.core.model.FailureHandling
import com.kms.katalon.core.configuration.RunConfiguration
import static com.kms.katalon.core.testcase.TestCaseFactory.findTestCase
import static com.kms.katalon.core.testobject.ObjectRepository.findTestObject
import static com.kms.katalon.core.testdata.TestDataFactory.findTestData
import internal.GlobalVariable as GlobalVariable
Map<String, String> suiteProperties = new HashMap<String, String>();
suiteProperties.put('id', 'Test Suites/TS1')
suiteProperties.put('name', 'TS1')
suiteProperties.put('description', '')
DriverCleanerCollector.getInstance().addDriverCleaner(new com.kms.katalon.core.webui.contribution.WebUiDriverCleaner())
DriverCleanerCollector.getInstance().addDriverCleaner(new com.kms.katalon.core.mobile.contribution.MobileDriverCleaner())
DriverCleanerCollector.getInstance().addDriverCleaner(new com.kms.katalon.core.cucumber.keyword.internal.CucumberDriverCleaner())
RunConfiguration.setExecutionSettingFile("C:\\Users\\qcq0264\\tmp\\spullabhotla\\MethodCodeTooLarge\\Reports\\TS1\\20190325_155544\\execution.properties")
TestCaseMain.beforeStart()
TestCaseMain.startTestSuite('Test Suites/TS1', suiteProperties, [new TestCaseBinding('Test Cases/TC1 - Iteration 1', 'Test Cases/TC1', [ 'campaign' : '59a5dd9c8b6d8947e0dc042a' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 2', 'Test Cases/TC1', [ 'campaign' : '59a5de761b761325901ac21b' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 3', 'Test Cases/TC1', [ 'campaign' : '59a5de781b761325901ac21c' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 4', 'Test Cases/TC1', [ 'campaign' : '59a5de9159846636ccce487b' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 5', 'Test Cases/TC1', [ 'campaign' : '59a5df15fc8c3d72bc6ff759' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 6', 'Test Cases/TC1', [ 'campaign' : '59a5e0582e067d4f30c910bb' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 7', 'Test Cases/TC1', [ 'campaign' : '59a5e07cf72e8e75643ec3b3' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 8', 'Test Cases/TC1', [ 'campaign' : '59a5e0c2dff8f04210f0b1ce' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 9', 'Test Cases/TC1', [ 'campaign' : '59a5e0d629e8e055a03805a6' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 10', 'Test Cases/TC1', [ 'campaign' : '59a5e10e7e52f9602ce9e3c7' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 11', 'Test Cases/TC1', [ 'campaign' : '59a5e11f498ff154b8ccc4d0' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 12', 'Test Cases/TC1', [ 'campaign' : '59a5e1474526846418e7032f' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 13', 'Test Cases/TC1', [ 'campaign' : '59a5e163878052655c073a1e' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 14', 'Test Cases/TC1', [ 'campaign' : '59a5e18978674e4b1cde132f' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 15', 'Test Cases/TC1', [ 'campaign' : '59a5e19a40ea6e693003ab48' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 16', 'Test Cases/TC1', [ 'campaign' : '59a5e1a6045bc02d0c5023cb' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 17', 'Test Cases/TC1', [ 'campaign' : '59a5e211ce45101ec032c648' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 18', 'Test Cases/TC1', [ 'campaign' : '59a5e29508eb7c0a94865a8f' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 19', 'Test Cases/TC1', [ 'campaign' : '59a5e335a7a714425ca3649d' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 20', 'Test Cases/TC1', [ 'campaign' : '59a704a41289a733b041a15b' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 21', 'Test Cases/TC1', [ 'campaign' : '59a704ba0ea5e74db41b8be9' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 22', 'Test Cases/TC1', [ 'campaign' : '59a708447a64e903bc8784d8' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 23', 'Test Cases/TC1', [ 'campaign' : '59a708547a64e903bc8784da' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 24', 'Test Cases/TC1', [ 'campaign' : '59a708ee0c87482a0466ee85' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 25', 'Test Cases/TC1', [ 'campaign' : '59a73f443298b351f84622d2' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 26', 'Test Cases/TC1', [ 'campaign' : '59a73faf4535402ef866f9bc' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/TC1 - Iteration 27', 'Test Cases/TC1', [ 'campaign' : '59a73fd56464ca2ee04c2239' , 'event' : 'Receive' , ]), new TestCaseBinding('Test Cases/T ........................................................
Obviously this is the implementation of the failing Test Suite. It has a terribly long literal of List<TestCaseBinding> which represents data in the CSV file. This is the cause of Method code too large!.
I believe you would find a similar TempTestSuitexxxxx.groovy file in your project.