ci: Migrate docker in docker arm64 runner tag (#1012)

We have completed the migration of the docker in docker arm64 runners to
MicroVMs on K8s. We can now re-use the original tag we had
`docker-in-docker:arm64`
to have alignment with the amd64 microVMs.
This is a cosmetic change that does not affect the functionality of the
runner.
Campaign ran by @jorgetomtz

Co-authored-by: campaigner-prod[bot] <87874424+campaigner-prod[bot]@users.noreply.github.com>

Author: campaigner-prod[bot]

.gitlab/templates/pipeline.yaml.tpl

@@ -330,7 +330,7 @@ signed layer bundle:
 build java lambdas:
   stage: integration-tests
   image: registry.ddbuild.io/images/docker:27.3.1
-  tags: ["docker-in-docker:microvm-arm64"]
+  tags: ["docker-in-docker:arm64"]
   rules:
     - when: on_success
   needs: []
@@ -349,7 +349,7 @@ build java lambdas:
 build dotnet lambdas:
   stage: integration-tests
   image: registry.ddbuild.io/images/docker:27.3.1
-  tags: ["docker-in-docker:microvm-arm64"]
+  tags: ["docker-in-docker:arm64"]
   rules:
     - when: on_success
   needs: []
@@ -368,7 +368,7 @@ build dotnet lambdas:
 build python lambdas:
   stage: integration-tests
   image: registry.ddbuild.io/images/docker:27.3.1
-  tags: ["docker-in-docker:microvm-arm64"]
+  tags: ["docker-in-docker:arm64"]
   rules:
     - when: on_success
   needs: []
@@ -387,7 +387,7 @@ build python lambdas:
 build node lambdas:
   stage: integration-tests
   image: registry.ddbuild.io/images/docker:27.3.1
-  tags: ["docker-in-docker:microvm-arm64"]
+  tags: ["docker-in-docker:arm64"]
   rules:
     - when: on_success
   needs: []