Ignore METADATA files in python packages shipped with prebuilts/clang, which...

Ignore METADATA files in python packages shipped with prebuilts/clang, which are from upstream and not in the format used in Android.

Bug: 376319250
Test: m nothing, out/.module_paths/METADATA.list should contain only two METADATA files in prebuilts/clang: prebuilts/clang/host/linux-x86/METADATA and prebuilts/clang/host/darwin-x86/METADATA
Change-Id: I9933ef44c91db7334f1a65374f718beacb044612