ICU-22849 Fix memLeak in RBBIRuleBuilder by using LocalMemory #33

Job	Run time
clang-valgrind-intltest (utility)	7m 3s
clang-valgrind-test	10m 24s
clang-valgrind-intltest (normalize)	6m 39s
clang-valgrind-intltest (collator)	5m 10s
clang-valgrind-intltest (regex)	5m 13s
clang-valgrind-intltest (format)	16m 30s
clang-valgrind-intltest (translit)	5m 49s
clang-valgrind-intltest (rbbi)	7m 28s
clang-valgrind-intltest (rbnf)	6m 2s
clang-valgrind-intltest (rbnfrt)	6m 17s
clang-valgrind-intltest (icuserv)	5m 2s
clang-valgrind-intltest (idna)	5m 10s
clang-valgrind-intltest (convert)	6m 42s
clang-valgrind-intltest (rbnfp)	5m 4s
clang-valgrind-intltest (csdet)	5m 1s
clang-valgrind-intltest (spoof)	5m 0s
clang-valgrind-intltest (bidi)	5m 26s
	1h 54m 0s

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