Update BlobStorePerfTests to use releaseAllLeases().

Earlier, we were clearing package data which has a
side effect of the package under instrumentation getting
killed.

Bug: 227589710
Test: atest ./apct-tests/perftests/blobstore/src/com/android/perftests/blob/BlobStorePerfTests.java
Change-Id: I6c43c4404939a8b7c35b2214ff2460f6513f08ba