Abandon other staged sessions when a rollback is staged.

This change causes all staged sessions that are not rollbacks to be
abandoned (failed) when a rollback is staged.

This will ensure that an SDK extension level dependency is not violated
if a rollback causes the extension level to drop while at the same time
an app is installed that depends on the higher extension level.

Other rollbacks are not failed so that multiple rollbacks can be staged
together.

Bug: 163734200
Test: atest RollbackManagerHostTest
Change-Id: Iffb50d2a05f6ab0b6691fc84ffc273c2faecb88b