Marking WearOS specific Content Provider as non exported

PIA has an old, unmaintained exported content provider. 3P apps could
use the activity system service to indirectly access this CP without the
required permissions.
To fix this, the content provider was marked non-exported.

Bug: 254845456
Test: Manual. Verified using the attached POC in the bug.
Change-Id: I37ee2977df36fad9a5edf6a58eb42cc4c78e1fc1