[Build] Restructure ironbank docker image build

We remove the shared dockerfile template in favor of a explicit ironbank image,
similar to default and wolfi images.

We also remove a test `test310IronBankImageHasNoAdditionalLabels` which basically just tested proper
distinction in our shared dockerfile which is now not required anymore.

This test started failing as redhat started to add org.opencontainers.image.revision tag

Author: breskeby

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/DockerBase.java

@@ -17,7 +17,7 @@ public enum DockerBase {
     DEFAULT("redhat/ubi9-minimal:latest", "", "microdnf", "dockerfiles/default/Dockerfile"),
 
     // The Iron Bank base image is UBI (albeit hardened), but we are required to parameterize the Docker build
-    IRON_BANK("${BASE_REGISTRY}/${BASE_IMAGE}:${BASE_TAG}", "-ironbank", "yum", "Dockerfile"),
+    IRON_BANK("${BASE_REGISTRY}/${BASE_IMAGE}:${BASE_TAG}", "-ironbank", "yum", "dockerfiles/ironbank/Dockerfile"),
 
     // Chainguard based wolfi image with latest jdk
     WOLFI(

distribution/docker/README.md

@@ -134,8 +134,11 @@ custom behaviour in the
 
 We go to some lengths to try and make the Docker build resilient to transient
 network errors. This is why, when browsing the
-[Dockerfile](src/docker/Dockerfile), you'll see many commands wrapped in looping
-logic, so that if e.g. package installation fails, we try again. We also perform
+[Dockerfile](src/docker/dockerfiles/wolfi/Dockerfile), you'll see many commands wrapped in looping
+logic, so that if e.g. package installation fails, we try again.
+Our default docker image and the Iron Bank image do not have this retry logic,
+because Dockerhub and Iron Bank asked for as concise as possible Dockerfiles.
+We also perform
 explicit `docker pull` commands instead of relying on `docker run` to pull an
 image down automatically, so that we can wrap the `pull` part in a retry.