Allow to close session from wrong context.

commitLocked runs on a handler, thereby as system. It will call close()
if the package installer is popped-up to confirm the installation. Hence
we have to allow this use case without checking the caller.

Bug: 64467704
Test: gts-tradefed run singleCommand gts -m GtsPackageInstallSessionTestCases
Change-Id: I0bd0329c0485c50afa459d90c3372d7bf7408287