ICU-22730 Fix int32_t overflow in Persian calendar #2859

Job	Run time
clang-valgrind-test	10m 11s
clang-valgrind-intltest (utility)	6m 50s
clang-valgrind-intltest (normalize)	6m 32s
clang-valgrind-intltest (collator)	5m 40s
clang-valgrind-intltest (regex)	5m 11s
clang-valgrind-intltest (format)	16m 29s
clang-valgrind-intltest (translit)	5m 42s
clang-valgrind-intltest (rbbi)	7m 35s
clang-valgrind-intltest (rbnf)	6m 25s
clang-valgrind-intltest (rbnfrt)	6m 16s
clang-valgrind-intltest (icuserv)	5m 32s
clang-valgrind-intltest (idna)	5m 35s
clang-valgrind-intltest (convert)	6m 38s
clang-valgrind-intltest (rbnfp)	5m 20s
clang-valgrind-intltest (csdet)	5m 20s
clang-valgrind-intltest (spoof)	5m 34s
clang-valgrind-intltest (bidi)	5m 52s
	1h 56m 42s

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