cubicweb #10468967 when started from the UI, source synchronization should be asynchronous [validation pending]

else it's not very user friendly and may hit http timeout

prioritynormal
typeenhancement
done in3.23.0
load left0.000
closed by#78c8e64f3cef [sources] synchronize source asynchronously when started from the UI
patch[sources] synchronize source asynchronously when started from the UI [applied]