Push app image via external URL if registry is exposed

[kwiatekus]

Description

Improve stability of pushing image into kyma's registry as part of kyma app push and registry image-import commands by using external url whenever external access is enabled.

Reasons

kyma app push when used with --code-path or --dockerfile option builds the app image and pushes it to kyma's docker registry via internal url and a local port-forward. This lacks stability.
In case docker registry is exposed, image push should happen via external url.

Attachment

kyma alpha app push --name bookstore --expose --container-port 3000 --mount-secret hana-hdi-binding --code-path sample-http-db-nodejs/bookstore
 
Importing bookstore:2025-03-13_16-06-26
Error:
  failed to import image to in-cluster registry

Error Details:
  failed to push image to the in-cluster registry: PUT https://localhost:32137/v2/bookstore/blobs/uploads/c0ae3d32-c861-4ed5-a796-43bf9434b954?_state=REDACTED&digest=sha256%3Acb4197092ed16fbdd56eafda1c0995d527ca3a0621d3b1787a1376e8478d751c: BLOB_UPLOAD_UNKNOWN: blob upload unknown to registry; map[]