test: improve test coverage for plugin-coverage #6178

Job	Run time
E2E tests (windows-latest)	2m 52s
E2E tests (ubuntu-latest)	1m 30s
Build	1m 34s
Format check	44s
E2E tests (macos-latest)	1m 19s
Linter	1m 6s
Unit tests (windows-latest)	1m 44s
Integration tests (macos-latest)	48s
Unit tests (ubuntu-latest)	49s
Integration tests (windows-latest)	1m 48s
Integration tests (ubuntu-latest)	46s
Unit tests (macos-latest)	45s
	15m 45s

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