btm_sec: Don't clear security record on encryption failed

Clearing keys will block future tries to enable encryption even on
reconnection unless Bluetooth is turned OFF/ON.

If stack does not remove bonding, it should also not invalidate keys.

Bug: 342516733
Bug: 342521414
Flag: com.android.bluetooth.flags.sec_dont_clear_keys_on_encryption_err
Test: mmm packages/modules/Bluetooth
Test: atest net_test_stack_btm
Change-Id: Ief94ca7a5937160d4436bffb7e7183189eb91a13