Remove unused Android.mk in MergeOnlyTest

After checking, the modules under these directories can not be built
because the upper-level directories lack Android.mk.
In addition, the format of the Android.mk in these directories is also
incorrect, and if it is included, it will cause the build to break.

Bug: 319565408
Test: N/A
Change-Id: I1a7b2fc2ad78bcbcd6cd3f65c0a5043656711dae