Revert "Turn gtest isolated true by default"

This reverts commit d2a9d884.

Reason for revert: DroidMonitor-triggered revert due to breakage https://android-build.googleplex.com/builds/quarterdeck?branch=git_master&target=aosp_bramble-userdebug&lkgb=8618360&lkbb=8620137&fkbb=8618374, bug b/233280626

Bug: 233280626
Change-Id: If56b36ea1c883415b90bd2153707cb69df29776e