ICU-22533 Update BRS instructions for tagging release #1193

Job	Run time
clang-valgrind-test	13m 5s
clang-valgrind-intltest (utility)	8m 25s
clang-valgrind-intltest (normalize)	6m 18s
clang-valgrind-intltest (collator)	8m 16s
clang-valgrind-intltest (regex)	5m 13s
clang-valgrind-intltest (format)	16m 9s
clang-valgrind-intltest (translit)	5m 43s
clang-valgrind-intltest (rbbi)	7m 12s
clang-valgrind-intltest (rbnf)	6m 27s
clang-valgrind-intltest (rbnfrt)	6m 4s
clang-valgrind-intltest (icuserv)	5m 4s
clang-valgrind-intltest (idna)	5m 19s
clang-valgrind-intltest (convert)	8m 14s
clang-valgrind-intltest (rbnfp)	5m 7s
clang-valgrind-intltest (csdet)	5m 48s
clang-valgrind-intltest (spoof)	6m 10s
clang-valgrind-intltest (bidi)	5m 2s
	2h 3m 36s

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