[libc++] Install locales in the build bot Docker images

This allows running the locale tests on the build bots.

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 756db3084bc188fe6c9ed90992880a95a049c63f
1 file changed