Work around caching issue for CI builds with both apr&apr-util #532

Job	Run time
Empty APLOGNO() test	43s
Default	3m 55s
All-static modules	4m 59s
Prefork MPM, all-modules (except cgid)	4m 56s
Worker MPM, all-modules	4m 40s
Shared MPMs, all-modules	4m 45s
Event MPM, all-modules, mod_cgid only	5m 58s
Event MPM, all-modules, no CMSG_DATA	4m 35s
Default, all-modules + install	5m 3s
Default, all-modules, random test order	4m 42s
GCC 10 maintainer-mode w/-Werror, install + VPATH	3m 51s
All-modules, APR 1.7.4, APR-util 1.6.3	8m 53s
APR 1.8.x, APR-util 1.7.x	6m 51s
Pool-debug	6m 57s
Shared MPMs (event), pool-debug, SSL/TLS variants	13m 57s
Shared MPMs (worker), pool-debug, SSL/TLS variants	11m 1s
Shared MPMs (prefork), pool-debug, SSL/TLS variants	11m 11s
litmus WebDAV tests	3m 5s
Regenerate ap_expr	6m 41s
APR 1.7.4, APR-util 1.6.3, LDAP	6m 23s
APR trunk thread debugging	5m 18s
UBSan	5m 30s
ASan	7m 53s
ASan, pool-debug	8m 13s
HTTP/2 test suite	14m 6s
MOD_TLS test suite	7m 16s
	2h 51m 22s

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