leaudio: Improve counting number of required CISes

After delivering patch:
b43a2d3e Add more configuration for single device with 2 ASEs

Media scenario allows also only 2 source ASEs.
Function get_cis_count in this case would combine Sink and Source ASEs
as a maximum required scenarion and would request from the controller 4
CISes.

This patch prevents this by taking into account
	* number of sink/source ASEs in the group
	* priority of the configurations.

Bug: 231084798
Test: atest BluetoothInstrumentationTests
Tag: #feature
Change-Id: I9dbf0a2f5ced51cf1e190ae76fe2e8ccbbe5688d