Add error log if FlowAggregator mode is updated dynamically #35489

Job	Run time
Check whether tests need to be run based on diff	24s
Verify docs and spelling	37s
Unit test (ubuntu-latest)	9m 7s
Golangci-lint (ubuntu-latest)	9m 20s
Integration test	5m 35s
Unit test (windows-2022)	16m 27s
Build Antrea and antctl binaries	13m 14s
Golangci-lint (macos-latest)	7m 9s
Check tidy, code generation and manifest	4m 19s
Build Antrea Windows binaries	2m 16s
Go benchmark test	5m 19s
	1h 13m 47s

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