Use after free in GATT TCB commands

Steps to reproduce: |-
1. Turn on BT
2. Pair and connect EATT suppoerted LEA remote
3. disconnect
4) reconnect remote

Repeat steps 3 and 4
-
Expected result: Reconnection should be successful
-
Observed result: Reconnection failing some times as Bluetooth reset while sending gatt responce

Root cuase: Stack trying to access already freed GATT TCB command queue

resolve: cleanup of GATT TCB command queue on disconnection

Flag: EXEMPT, strict check without logical change
Bug: 382606738
Test: atest bluetooth_test_gd_unit

Change-Id: I44c336d05e6c84d92f67316e23d78214c4e7b1a0