SystemServer: keep gatt apps when scan disallowed

When disallowing "scan while bluetooth is OFF", if bluetooth is ON, it
make no sense to disconnect the apps.
This change will keep the apps connected.

If bluetooth is in ble states, it also doesn't make sense because we are
gonna shut off the bluetooth anyway. So gatt will proceed to the
registration on its own

Bug: 379166793
Bug: 378031425
Test: m . | no test for API user journey yet
Flag: com.android.bluetooth.flags.ble_scan_setting_does_not_disconnect_if_bt_on
(cherry picked from https://android-review.googlesource.com/q/commit:f54c6915f8eda6e6165b4c04dad779a7a57b7a25)
Merged-In: I982571e5f0e457cf6ee927393eca01185658c834
Change-Id: I982571e5f0e457cf6ee927393eca01185658c834