Bluetooth: Tests: Check CCC Store

The first test check that if a bonded peer subscribe to a CCC, this
change is correctly stored to flash.

The second test, which is currently failing, is included to reproduce a
bug that occur when CCC or CF store on write is disabled and the other
one is enabled, leading to the delayed store being enabled. Causing the
value of the corresponding `n` selected option to not be stored at all.

Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>