Populate error message if apexd.markStagedSessionReady fails

Test: atest CtsStagedInstallHostTestCases
Bug: 136548037
Bug: 122952270

Change-Id: Ia7823c4334f77b3cd3f66f1c6a9f3cc32250b805
Merged-In: I6fde70418990ee27c1966619badc437c9bffb697
(cherry picked from commit ab4d7354ea374fed6261e107be90bb349ea48c49)
2 files changed