Test

use `IS_SLASH` in various places instead of string comparing #1905

Job	Run time
Generate Matrix	9s
Suite / MACOS_ARM64_DEBUG_NTS	14m 6s
Suite / ALPINE_X64_ASAN_DEBUG_ZTS	22m 35s
Suite / LINUX_X32_DEBUG_ZTS	11m 0s
Suite / LINUX_X64_ASAN_DEBUG_ZTS	41m 31s
Suite / LINUX_X64_RELEASE_NTS	12m 47s
Suite / WINDOWS_X64_ZTS	34m 33s
Suite / BENCHMARKING	11m 42s
Suite / COVERAGE	0s
Suite / FREEBSD_NTS	12m 8s
Suite / LIBMYSQLCLIENT	0s
Suite / SOLARIS	0s
Suite / LINUX_PPC64_ASAN_DEBUG_ZTS	0s
Suite / COMMUNITY_${{ matrix.type }}	0s
Suite / MSAN	0s
Suite / OPCACHE_VARIATION	0s
Suite / PECL	-1s
	2h 40m 30s

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