test: clear tap instance caches between test runs again #25927

Job	Run time
syntax	52s
tap syntax	4m 57s
docker	4m 20s
formula audit	6m 28s
cask audit	2m 20s
vendored gems	49s
test default formula (Ubuntu 22.04)	4m 7s
tests (online)	7m 58s
test default formula (Ubuntu 20.04)	5m 21s
update-test (Ubuntu 22.04)	1m 51s
tests (generic OS)	5m 39s
test default formula (macOS 13 x86_64)	2m 30s
update-test (macOS 13)	49s
tests (Ubuntu 22.04)	5m 57s
test default formula (macOS 14 arm64)	1m 18s
tests (Ubuntu 20.04)	6m 16s
tests (macOS 13 x86_64)	7m 56s
tests (macOS 14 arm64)	9m 1s
	1h 18m 29s

Provide feedback