ICU-23000 Replace CharString for LocaleBased #170

Job	Run time
clang-valgrind-test	10m 11s
clang-valgrind-intltest (utility)	7m 12s
clang-valgrind-intltest (normalize)	6m 29s
clang-valgrind-intltest (collator)	5m 29s
clang-valgrind-intltest (regex)	5m 29s
clang-valgrind-intltest (format)	16m 45s
clang-valgrind-intltest (translit)	6m 10s
clang-valgrind-intltest (rbbi)	8m 13s
clang-valgrind-intltest (rbnf)	6m 32s
clang-valgrind-intltest (rbnfrt)	6m 31s
clang-valgrind-intltest (icuserv)	5m 14s
clang-valgrind-intltest (idna)	5m 31s
clang-valgrind-intltest (convert)	7m 0s
clang-valgrind-intltest (rbnfp)	5m 34s
clang-valgrind-intltest (csdet)	5m 48s
clang-valgrind-intltest (spoof)	5m 46s
clang-valgrind-intltest (bidi)	5m 42s
	1h 59m 36s

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