Fix `upload-sarif` potentially initialising CodeQL twice #4616

Job	Run time
Diagnostic export (macos-latest, nightly-latest)	1m 34s
Diagnostic export (macos-latest, linked)	1m 23s
Diagnostic export (windows-latest, linked)	3m 6s
Diagnostic export (ubuntu-latest, linked)	1m 20s
Diagnostic export (ubuntu-latest, nightly-latest)	1m 22s
Diagnostic export (windows-latest, nightly-latest)	3m 5s
	11m 50s

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