builder/azure: Remove double override of GalleryImageVersionsClient.PollDuration
builder/azure: Remove double override of GalleryImageVersionsClient.PollDuration

This change fixes an issues where custom timeouts set for the
GalleryImagesVersionClient was being over written by the default client
poll duration.

rnaveiras/packer,dave2/packer,dave2/packer,grubernaut/packer,paulmey/packer,hashicorp/packer,rnaveiras/packer,rnaveiras/packer,rnaveiras/packer,pecigonzalo/packer,hashicorp/packer,pecigonzalo/packer,grubernaut/packer,mitchellh/packer,ricardclau/packer,ricardclau/packer,paulmey/packer,rnaveiras/packer,paulmey/packer,pecigonzalo/packer,ricardclau/packer,paulmey/packer,mitchellh/packer,ricardclau/packer,mitchellh/packer,dave2/packer,grubernaut/packer,hashicorp/packer,mitchellh/packer,paulmey/packer,dave2/packer,hashicorp/packer,mitchellh/packer,grubernaut/packer,rnaveiras/packer,ricardclau/packer,paulmey/packer,grubernaut/packer,ricardclau/packer,dave2/packer,dave2/packer,grubernaut/packer,pecigonzalo/packer