ICU-22977 Rollback to windows-2019 temporarily to unblock CI #3084

Job	Run time
clang-valgrind-intltest (utility)	6m 58s
clang-valgrind-intltest (normalize)	7m 13s
clang-valgrind-intltest (collator)	5m 35s
clang-valgrind-intltest (regex)	5m 43s
clang-valgrind-test	10m 35s
clang-valgrind-intltest (format)	16m 18s
clang-valgrind-intltest (translit)	5m 43s
clang-valgrind-intltest (rbbi)	8m 2s
clang-valgrind-intltest (rbnf)	6m 44s
clang-valgrind-intltest (rbnfrt)	6m 24s
clang-valgrind-intltest (icuserv)	5m 27s
clang-valgrind-intltest (idna)	5m 30s
clang-valgrind-intltest (convert)	6m 49s
clang-valgrind-intltest (rbnfp)	5m 12s
clang-valgrind-intltest (csdet)	5m 33s
clang-valgrind-intltest (spoof)	5m 22s
clang-valgrind-intltest (bidi)	5m 28s
	1h 58m 36s

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