cubicweb-vcsfile #3915240 hide obsolete/hidden heads in description tab (repo primary view) [validation pending]

Any repo that uses mutable history will likely have hundreds of hidden heads compared to actual visible heads (usually only a handful).

prioritynormal
typebug
done in2.0.0
load0.500
load left0.000
closed by#808fabb57e1b [views] don't count hidden changesets as heads (closes #3915240)
patch[views] don't count hidden changesets as heads (closes #3915240) [applied]