leaudio: Fix bonding during phone call for SwB support

When bonding set of earbuds while phone call it could happen that for
first bonded device 32kHz support was choosen even the whole set should
have 16kHz when both devices are in the streaming.

This patch fixes that, by looking into CSIP Desired group size when
configuring first bonded device.

Bug: 335808484
Test: atest bluetooth_le_audio_test
Flag: Exempt, regression tested with unit tests, newt test added
Change-Id: I5e2126c233a4246c6bf58b8ee9035f304af1ba26