Eatt: Improve colision handling

With this patch we make sure to act on the collision only whe there is
no pending channels and all the requested channels has been rejected.

Bug: 237399985
Test: L2CAP PTS tests
Test: atest BluetoothInstrumentationTests
Tag: #feature
Merged-In: Iff0818bbef1a684f7cb1740584a14c9457a3cde1
Change-Id: Iff0818bbef1a684f7cb1740584a14c9457a3cde1
(cherry picked from commit 5c6f21c9)