Add `npm run ava` command, update instructions, and exclude files from VSCode search #5826

Job	Run time
Go: tracing with custom build steps (ubuntu-latest, stable-v2.17.6)	1m 20s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.20.7)	1m 35s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.21.4)	59s
Go: tracing with custom build steps (macos-latest, default)	2m 28s
Go: tracing with custom build steps (macos-latest, stable-v2.20.7)	2m 7s
Go: tracing with custom build steps (macos-latest, linked)	3m 9s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.19.4)	1m 15s
Go: tracing with custom build steps (macos-latest, stable-v2.21.4)	3m 9s
Go: tracing with custom build steps (macos-latest, stable-v2.17.6)	3m 4s
Go: tracing with custom build steps (macos-latest, stable-v2.19.4)	3m 7s
Go: tracing with custom build steps (ubuntu-latest, nightly-latest)	58s
Go: tracing with custom build steps (ubuntu-latest, linked)	1m 3s
Go: tracing with custom build steps (macos-latest, stable-v2.18.4)	2m 52s
Go: tracing with custom build steps (macos-latest, stable-v2.22.4)	2m 4s
Go: tracing with custom build steps (macos-latest, nightly-latest)	3m 18s
Go: tracing with custom build steps (ubuntu-latest, default)	1m 2s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.18.4)	1m 17s
Go: tracing with custom build steps (ubuntu-latest, stable-v2.22.4)	1m 10s
	35m 57s

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