chore(controller): remove a Go 1.15 env var that no longer exists (#1… #20430

Job	Run time
argoexec-image	2m 32s
Get changed files	6s
Lint	3m 40s
Unit Tests	4m 7s
Windows Unit Tests	8m 45s
Codegen	0s
UI	0s
E2E Tests (test-executor, minimal)	13m 55s
E2E Tests (test-corefunctional, minimal)	12m 48s
E2E Tests (test-functional, minimal)	19m 12s
E2E Tests (test-api, mysql)	6m 52s
E2E Tests (test-cli, mysql)	11m 21s
E2E Tests (test-cron, minimal)	7m 29s
E2E Tests (test-examples, minimal)	5m 53s
E2E Tests (test-plugins, plugins)	3m 42s
E2E Tests (test-java-sdk, minimal)	3m 28s
E2E Tests (test-python-sdk, minimal)	3m 13s
E2E Tests (test-executor, v1.25.11-k3s1, minimal)	13m 34s
E2E Tests (test-corefunctional, v1.25.11-k3s1, minimal)	13m 4s
E2E Tests (test-functional, v1.25.11-k3s1, minimal)	20m 7s
E2E Tests - Composite result	1s
	2h 33m 49s

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