MockContentProvider.getIContentProvider is a private API

With I14cf217f21fd3534c920c3a6336cf2d14c02e60c, the private APIs from
android.test.* libs become inaccessible. In addition to that,
MockContentProvider.getIContentProvider which was one of the private
APIs gets default implementation. Since there is no need for this test
to provide the implementation via overriding, drop the overriding
method.

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

Bug: 157007292
Test: m
Merged-In: I25b8dd8226963306e9a38b74f74e8c74b83bd7ff
(cherry picked from commit c85efed61c8c5001c92bb4f22b9b944e205b3980)
Change-Id: I25b8dd8226963306e9a38b74f74e8c74b83bd7ff
1 file changed