The command to delete unused third_party/ directories needs to be more
specific to delete unused third_party/vulkan-deps/ directories.

Additionally, use the flag '-path', since that's more portable than
'-wholename' which is GNU-specific.

Bug: b/187342779
Change-Id: Ie8b02360d0d86f9b42141212aaa6c2aa27a063c1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2965605Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>