GD-SL4A: Add repeated connection test for background connections

* Add test_autoconnect_gatt_without_pairing_and_disconnect_quickly
  to check if GATT is tear down fast enought after last client
  unregisters
* Add test_autoconnect_gatt_twice_with_random_address_without_pairing
  to check if we can make subsequent GATT connections
* Both tests are for random address that are unbonded

Bug: 232258524
Test: gd/cert/run --sl4a GattConnectLowLayerTest.test_autoconnect_gatt_twice_with_random_address_without_pairing
Test: gd/cert/run --sl4a GattConnectLowLayerTest.test_autoconnect_gatt_without_pairing_and_disconnect_quickly
Test: gd/cert/run --sl4a GattConnectLowLayerTest.test_disconnect_autoconnect_without_close
Test: gd/cert/run --sl4a GattConnectLowLayerTest.test_autoconnect_without_proactive_disconnect
Test: gd/cert/run --sl4a GattConnectLowLayerTest.test_autoconnect_without_proactive_disconnect_repeatedly
Tag: #bug-fix
Merged-In: Iad813154d87c4bb18e7762b8a4c5ef414979b8e8
Change-Id: Iad813154d87c4bb18e7762b8a4c5ef414979b8e8
(cherry picked from commit 2a2172d4)