Bluetooth: TBS: Clear pending notifications on unsub

[Hanliang-Xu]

If the client removes its subscription to any of the TBS characteristics at any time, the pending appropriate flags are now being cleared.

Fixes #104511

[github-actions]

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud