Tidy up CtsAppSecurityHostTestCases for PM test plan

According to the go/audit_pm_test_plan_sheet_2021, the following tests
are necessary to run for the presubmit process.
* android.appsecurity.cts.ApkVerityInstallTest (ag/15434575)
* android.appsecurity.cts.AppSecurityTests (ag/16473520)
* android.appsecurity.cts.ApplicationVisibilityTest (ag/15151833)
* android.appsecurity.cts.EphemeralTest (ag/16097868)
* android.appsecurity.cts.ExternalStorageHostTest (ag/16473520)
* android.appsecurity.cts.InstantAppUserTest (ag/16097868)
* android.appsecurity.cts.IsolatedSplitsTests (ag/15509173)
* android.appsecurity.cts.OverlayHostTest (ag/15938874)
* android.appsecurity.cts.PackageVisibilityTest (ag/15461803)
* android.appsecurity.cts.PkgInstallSignatureVerificationTest
  (ag/16095666)
* android.appsecurity.cts.PrivilegedUpdateTests (ag/15744081)
* android.appsecurity.cts.SharedUserIdTest (ag/7013394)
* android.appsecurity.cts.SplitTests (ag/15509173)

CtsAppSecurityHostTestCases contains some tests not belonging
to PackageManager. It annotates @Presubmit for those classes belonging
to PackageManager. It will be triggered via
frameworks/base/core/java/android/content/pmTEST_MAPPING by the
presubmit process.

Test: TP="CtsAppSecurityHostTestCases:android.appsecurity.cts"; atest \
     ${TP}.ApkVerityInstallTest \
     ${TP}.AppSecurityTests \
     ${TP}.ApplicationVisibilityTest \
     ${TP}.EphemeralTest \
     ${TP}.ExternalStorageHostTest \
     ${TP}.InstantAppUserTest \
     ${TP}.IsolatedSplitsTests \
     ${TP}.OverlayHostTest \
     ${TP}.PackageVisibilityTest \
     ${TP}.PkgInstallSignatureVerificationTest \
     ${TP}.PrivilegedUpdateTests \
     ${TP}.SharedUserIdTest \
     ${TP}.SplitTests

Bug: 180650365
Change-Id: I0b626e311a598d0fb953019a016a1dbafc380f81