dev-cmd/tests: skip tests that require core if it's not tapped #27282

Job	Run time
syntax	56s
cask audit	3m 1s
vendored gems	46s
formula audit	6m 15s
docker	4m 16s
tap syntax	4m 41s
test default formula (Ubuntu 22.04)	4m 15s
tests (online)	8m 44s
test default formula (Ubuntu 20.04)	5m 47s
update-test (Ubuntu 22.04)	1m 3s
tests (generic OS)	5m 44s
test default formula (macOS 13 x86_64)	2m 32s
update-test (macOS 13)	51s
tests (Ubuntu 22.04)	6m 16s
test default formula (macOS 14 arm64)	1m 30s
tests (Ubuntu 20.04)	6m 51s
tests (macOS 13 x86_64)	8m 18s
tests (macOS 14 arm64)	9m 23s
	1h 21m 9s

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