Use //build/bazel/platforms/os:linux_glibc for osLinux

osLinux is implicitly glibc, use //build/bazel/platforms/os:linux_glibc
for the configurability select key for it.

Bug: 259266326
Test: build/bazel/ci/mixed_libc.sh
Test: USE_HOST_MUSL=true build/bazel/ci/mixed_libc.sh
Change-Id: Ifbd121ab3d943f3fdfbd3f6c3e982d1eaaaa9ec1