GpuStats: Track ANGLE usage info

This change enables tracking for ANGLE usage and driver loading. This change
also removes a redundant api and some redundant logics, because driver loading
in GL loader has been cleaned up.

Bug: 132285967
Test: enable angle and dumpsys gpu
Change-Id: Idf20e86ddfb471a218d5ccd09a0e63f697e60274