Revert "Prevent flag optimization in the app"

This reverts commit 780678c4.

Reason for revert: Temporary fix is not needed anymore

Now that the test is re-building the source, it should be possible to optimize the app again.

Relevant changes that allows this: https://r.android.com/3501909

Bug: 395691070
Bug: 383863941
Change-Id: I3d339647ea47852c1eac43adc9683f589f252815
Test: atest BluetoothJavaUnitTests
Test: will be verified by atp run on release target
Flag: Exempt - mainline and app optimization