Fix replicated_regions not using shared_image_gallery_replica_count for build location when its specified in the list

[JenGoldstrich]

The logic that handles the backwards compatibility for creating the new Target Regions block from the replicated regions list doesn't add the replica count to the default region. This causes the default region to always have a replica count of 1, this is currently a bit iffy to unit test and should probably be unwound into its own step still, but I don't think we should leave this functionality broken in the mean time

[nywilken]

I see what you are doing here. Maybe this changed with an upstream API change but when I first tested b.config.SharedGalleryImageVersionReplicaCount is used as the default replica count if a target region is left unset. But I see you are just reusing the value so that they match for the default build target.

[JenGoldstrich]

So to clarify, this is only for the global replica case, since setting the replica_count field is not allowed when setting target_regions

We actually send this currently for the build region if its not specified in the replication_regions, the plugin then adds it to the replication regions here

packer-plugin-azure/builder/azure/arm/builder.go

Lines 272 to 279 in 4d2a020

	// SIG requires that replication regions include the region in which the created image version resides
	if foundMandatoryReplicationRegion == false {
	normalizedRegions = append(normalizedRegions, TargetRegion{
	Name: buildLocation,
	DiskEncryptionSetId: b.config.DiskEncryptionSetId,
	ReplicaCount: b.config.SharedGalleryImageVersionReplicaCount,
	})
	}

, so this is inconsistent based on when we specify the build location in that list or not, which is incorrect logic.

I think we should clean this up more, to just pass in the raw values the API expects, but I need to do more research and refactoring, so I am going to merge this for now to fix the bug