fix incremental installation test

1) Removed property test because CTS tests does not have permission to
reset properties or permission to read IncFs_Enabled via jni.
2) Use system property to check if incfs is available.
3) Updated the test files.

BUG: 150476123
Test: atest PackageManagerShellCommandIncrementalTest
Change-Id: Ic2a1d2ce7565eb7fa4bd4327d021551ba26dd110
(cherry picked from commit 71a57b7c6c8abec55c2b287d690dc93f68db5c7f)
3 files changed