Revert "gatt: Improve queueing of GATT messages"

Revert submission 2268950

Bug: 257046947
Bug: 249431973
Test: reverting changes that broke earlier build
Reason for revert: b/257046947 infinite loop
Reverted Changes:
If19de77a8:gatt: Improve queueing of GATT messages
I1bfb4c546:gatt: Remove reduntant `in_use` flag
I1d3351ebc:gatt: Improve send queued request from tGATT_TCB

Change-Id: Ie898cf668476edfc09b8d94218bab16116268810