adb-remount-test: Strengthen skip_administrative_mounts

Refactor skip_administrative_mounts so that it filters by device name,
mount point and filesystem type. (Was filtering by device name and mount
point.)

We need this because pseudo filesystems such as tmpfs and overlayfs can
have free-formed device name:

  blah /mnt/mnt_point overlay ro,lowerdir=...

However the filesystem type (third field of /proc/mounts) must be
reflecting the actual filesystem, so to robustly filter out
administrative filesystems, we have to check the filesystem type field.

Bug: 188862155
Test: adb-remount-test.sh
Change-Id: I5058cbe8a36920f25b73a5d5833e9fc5a096e90f