Allowlist TelephonyProvider HSUM backup&restore

Allow TelephonyProvider to be eligible for backup&restore on non-user-0
for HSUM devices, since on HSUM the provider really belongs to the
MainUser.

Test: manual backup and restore of messages on HSUM device
Bug: 369560193
Flag: EXEMPT bugfix
Change-Id: I4dfd4287a1f291b8c7ec3c2075a109696ffb8baa