Automated cherry pick of #6077: Fix nil pointer dereference when ClusterGroup/Group is used #31465

Job	Run time
Check whether tests need to be run based on diff	23s
Verify docs and spelling	36s
Unit test (ubuntu-latest)	6m 2s
Integration test	9m 57s
Go benchmark test	4m 27s
Build Antrea and antctl binaries	9m 27s
Golangci-lint (macos-latest)	10m 25s
Golangci-lint (ubuntu-latest)	7m 29s
Check tidy, code generation and manifest	5m 18s
Build Antrea Windows binaries	1m 40s
Unit test (windows-2022)	12m 58s
	1h 8m 42s

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