cubicweb-collaboration #3670234 Do not set the site title in postcreate [validation pending]

Indeed, the collaboration cube is not supposed to be used in a stand-alone manner. Hence, it should not set the site title.

prioritynormal
typebug
done in0.2.0
load0.100
load left0.000
closed by#ce4b98f38070 Drop site-title setting in postcreate (closes #3670234).
patchDrop site-title setting in postcreate (closes #3670234). [applied]