Don't run apex_available check for coverage builds

Coverage build adds extra dependencies for the runtime libs. Marking
them and their transitive dependenciese with apex_available doesn't make
any value; it instead adds noise.

Exempt-From-Owner-Approval: cherry-pick from AOSP

Bug: 150999716
Test: m
Merged-In: I08e51cec1de6ded624ef9d4c41c1e5b2e611ff38
(cherry picked from commit 58d10900)
Change-Id: I08e51cec1de6ded624ef9d4c41c1e5b2e611ff38