ci: Provide basic .pipeline/config.yaml

Migrate away from deprecated service-pipeline-test and
service-pipeline-test-and-publish jobs in favor of bespoke PipelineLib
based pipelines.

See https://wikitech.wikimedia.org/wiki/PipelineLib/Guides/How_to_configure_CI_for_your_project

Bug: T307507
Change-Id: I097559149ff92e85e35d1bec8673cc81226e9416

.pipeline/config.yaml

@@ -0,0 +1,17 @@
+pipelines:
+  test:
+    blubberfile: blubber.yaml
+    stages:
+      - name: test
+        build: test
+        run: true
+  publish:
+    blubberfile: blubber.yaml
+    stages:
+      - name: test
+        build: test
+        run: true
+      - name: publish
+        build: production
+        publish:
+          image: true