Fix `upload-sarif` potentially initialising CodeQL twice #4599

Job	Run time
Diagnostic export (macos-latest, linked)	2m 3s
Diagnostic export (windows-latest, nightly-latest)	3m 41s
Diagnostic export (windows-latest, linked)	3m 20s
Diagnostic export (macos-latest, nightly-latest)	1m 32s
Diagnostic export (ubuntu-latest, nightly-latest)	1m 28s
Diagnostic export (ubuntu-latest, linked)	1m 17s
	13m 21s

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