Only apply standard swift settings on valid targets #24

Job	Run time
Cxx interop / Construct Cxx interop matrix	3s
Unit tests / Construct unit test matrix	2s
Soundness / Unacceptable language check	5s
Soundness / Documentation check	2m 58s
Soundness / API breakage check	4m 27s
Soundness / Broken symlinks check	3s
Soundness / Format check	36s
Soundness / License headers check	4s
Soundness / Shell check	31s
Cxx interop / Swift 6 language mode	2m 36s
Soundness / YAML lint check	5s
Soundness / Python lint check	5s
Cxx interop / Cxx interop / Linux (5.9)	2m 32s
Cxx interop / Cxx interop / Linux (5.10)	2m 33s
Cxx interop / Cxx interop / Linux (6.0)	2m 43s
Cxx interop / Cxx interop / Linux (nightly-next)	3m 25s
Cxx interop / Cxx interop / Linux (nightly-main)	3m 28s
Unit tests / Unit tests / Linux (5.9)	2m 22s
Unit tests / Unit tests / Linux (5.10)	2m 19s
Unit tests / Unit tests / Linux (6.0)	2m 46s
Unit tests / Unit tests / Linux (nightly-next)	3m 15s
Unit tests / Unit tests / Linux (nightly-main)	3m 15s
	40m 13s

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