cleaner: rewrite pkg-config file Cellar paths and keg-only #30573

Job	Run time
syntax	54s
formula audit	4m 44s
cask audit	2m 20s
tap syntax	7m 52s
test default formula (Ubuntu 22.04)	1m 35s
tests (online)	5m 44s
test default formula (Ubuntu 20.04)	3m 18s
update-test (Ubuntu 22.04)	24s
tests (generic OS)	2m 55s
vendored gems	40s
test default formula (macOS 13 x86_64)	2m 33s
update-test (macOS)	29s
tests (Ubuntu 22.04)	3m 28s
test default formula (macOS 15 arm64)	1m 33s
tests (Ubuntu 20.04)	3m 56s
tests (macOS 13 x86_64)	6m 54s
tests (macOS 15 arm64)	5m 2s
	54m 21s

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