FAPI TEST: rework test certificate creation #528

Job	Run time
scanbuild	6m 26s
coverity-test	0s
test-coverage	4m 45s
build-test (ubuntu-18.04, gcc)	4m 17s
build-test (ubuntu-18.04, clang)	4m 38s
test-fuzz	2m 28s
test-mbedtls (ubuntu-20.04)	2m 48s
build-test (ubuntu-20.04, gcc)	4m 29s
test-no-crypto-build	1m 20s
test-mbedtls (ubuntu-22.04-mbedtls-3.1)	2m 54s
build-test (ubuntu-20.04, clang)	4m 18s
test-tcti-config	13m 47s
build-test (fedora-32, gcc)	4m 39s
build-test (fedora-32, clang)	5m 10s
build-test (opensuse-leap, gcc)	4m 31s
build-test (opensuse-leap, clang)	4m 38s
build-test (ubuntu-22.04, gcc)	4m 14s
build-test (ubuntu-22.04, clang)	4m 31s
build-test (alpine-3.15, gcc)	3m 58s
build-test (alpine-3.15, clang)	4m 49s
	1h 28m 40s

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