Optimize resolution of single non-generic construct signatures #6543

Job	Run time
build	2m 34s
extension	44s
lint (ubuntu-latest)	3m 48s
lint (windows-latest)	9m 42s
lint (noembed)	3m 50s
baselines	6m 58s
misc	1m 4s
generate	3m 53s
test (no submodules)	5m 32s
test (ubuntu-latest)	8m 26s
test (concurrent test programs)	8m 33s
test (race mode)	14m 18s
tidy	1m 7s
test (windows-latest)	16m 13s
format	3m 3s
test (noembed)	6m 38s
test (macos-latest)	9m 32s
smoke	5m 23s
required	2s
	1h 51m 20s

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