Cronet: Merge apk_under_test into instrumentation_test_apk targets

Except for sample_apk, which looks like it's a valid app on its own.

Motivation:
 * Trying to add a new JNI generator, and these targets were being
 difficult due to the tests having (unused) native methods that the
 under_test apk did not have.
 * The under_test apks didn't really make sense on their own anyways, so
 it's more efficent to just combine them.

Bug: 898261
Change-Id: I23571ea61230daefccb8e0e14689d3f872080136
Reviewed-on: https://chromium-review.googlesource.com/c/1352853
Reviewed-by: Paul Jensen <pauljensen@chromium.org>
Commit-Queue: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612791}
4 files changed