leaudio: Minor cleanup on stream reconfiguration

No functional change as reconfiguration is always scheduled when new
configuration is known and is different from the previous one.
This patch is a preparation for the next patch.

Bug: 323275279
Flag: Exempt, no functional change. Regression tested with unittests
Test: atest bluetooth_le_audio_client_test
Change-Id: I7b45182a7353e3cc924717b3256dad8e7fee3d13