Remove package name from ROLLBACK_EXECUTED broadcast.

The receiver of the broadcast would likely want to query the rolled back
packages via RollbackManager regardless, and it's not clear which
package to put when an atomic set of packages is rolled back.

Bug: 112431924
Test: atest RollbackTest
Change-Id: Ic8db00b62d8993e00a0dd2cb79ae68c430b45bb8