Adjust testMutate to not rely on undefined behavior

It's not required that getDrawable return a shared state drawable,
so don't CTS test that state is shared across all instances

Also split the test into 2 smaller pieces.

Test: this
Bug: 158839504
Bug: 185178568
Bug: 196949739
Change-Id: Ifa2887a0c6735a538913e88319bd8c492cc21926
(cherry picked from commit 792ca25116b00f2f709e48f527c478760aa68b64)