GH-49772: [C++] Bump bundled mimalloc version (#49801) #6527

Job	Run time
check-labels / Check labels	4s
ODBC Linux	2m 35s
JNI macOS	8m 45s
JNI ubuntu-24.04-arm arm64v8	29m 35s
JNI ubuntu-latest amd64	37m 11s
ODBC release ARM64 macOS 14	7m 26s
ODBC debug AMD64 macOS 15-intel	1h 21m 0s
ODBC debug ARM64 macOS 14	9m 28s
ODBC release AMD64 macOS 15-intel	1h 4m 16s
AMD64 Alpine Linux	8m 1s
ODBC Windows	42m 52s
AMD64 Ubuntu Meson	3m 36s
AMD64 Debian C++23	8m 44s
AMD64 Ubuntu Large Memory Tests	45m 53s
ARM64 Windows 11 MSVC / windows	28m 24s
ODBC release	0s
ODBC nightly	0s
report-extra-cpp	-1s
	6h 17m 49s

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