Load gatt_database if it is empty in bta_gattc_process_indicate

If Service Changed indication is received but gatt_database is empty,
will try to load database from storage.

Bug: 131814072
Bug: 134994428
Test: 1.CTS Bluetooth LE Secure Test. 2.Unit test.
3. Pair BLE device via APP. 4. Pair device via Bluetooth Setting

Change-Id: Id3f3f0f33d5e0469a6f2ac6612fa9f5ea0b24142
Merged-In: Id3f3f0f33d5e0469a6f2ac6612fa9f5ea0b24142