Add session cleanup tests for multi-package sessions (2/n)

* reland ag/16279973
* disable the assertion since destroy() could be called
  on a child session.

Bug: 173194203
Test: atest StagedInstallInternalTest
Test: atest CtsRootRollbackManagerHostTestCases
Change-Id: I810612ef64adcd6fd3140faca967f7e9391a6289