TBS: Fix unauthorized access response

Previously the TBS access request resulted in no response from the stack
which resulted in ATT Timeout. With this change we respond with
insufficient authorization.

Bug: 263372634
Test: manual and atest BluetoothInstrumentationTests
Tag: #feature
Change-Id: I8e1a8e2ff6322099d8ccca44ddd47b7286703a16