Revert "fs_mgt: Fix remount failure in case of non-overlayfs system"

This reverts commit 588fe9e8.

Reason for revert: definite cause for test failure

Test: adb-remount-test.sh
Bug: 138407617
Fixes: 138622072
Change-Id: If2fee8873dd7d4360e7ff5572a0481247beffbca