Replace getContext with getTargetContext

The help methods should run in the context of the target app instead
of instrumentation app.

Bug: 176138594
Test: atest StagedInstallTest
Test: atest StagedRollbackTest
Test: atest RollbackManagerHostTest
Test: atest PackageManagerQueryPropertyTest
Test: atest TranscodeTestUtils
Test: atest PackageManagerGetPropertyTest
Test: atest PackageInstallerTest
Test: atest SecureFrpInstallTest
Test: atest InstallUtilTest

Change-Id: Ie756ba09f0776a227b43cc366b1f6c9305ca53b7
3 files changed