ICU-22929 Improve fuzzer to find leak from udat_open #67

Job	Run time
clang-valgrind-intltest (utility)	1s
clang-valgrind-test	1s
clang-valgrind-intltest (normalize)	4m 5s
clang-valgrind-intltest (collator)	4m 50s
clang-valgrind-intltest (regex)	19s
clang-valgrind-intltest (format)	4m 47s
clang-valgrind-intltest (translit)	1s
clang-valgrind-intltest (rbbi)	4m 0s
clang-valgrind-intltest (rbnf)	1m 45s
clang-valgrind-intltest (rbnfrt)	1m 30s
clang-valgrind-intltest (icuserv)	4m 10s
clang-valgrind-intltest (idna)	4m 6s
clang-valgrind-intltest (convert)	4m 48s
clang-valgrind-intltest (rbnfp)	1m 37s
clang-valgrind-intltest (csdet)	4m 47s
clang-valgrind-intltest (spoof)	1s
clang-valgrind-intltest (bidi)	4m 49s
	45m 37s

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