Unregister gatt server also in GATT unregAll API

Steps to reproduce: |-
1. Turn OFF BT
2. Turn ON BLE
3. Turn ON BT
4. Repeat steps 1-3 multiple times

Repro rate:  3/10 times

Observed result: BT on failing due to timeout

Root cause: Gatt server registration failing as gatt server not unregistered in BLE on scenario

Fix:  unregister gatt server also in GATT unregAll API

bug: 384654361
Test: m Bluetooth
Flag: EXEMPT, trivial

Change-Id: I241d5fce6b612ae27c526274a13fa6f36411f4e6