Name and dockerfile as required inputs. (#12161)

* Name and dockerfile path of image to build must be provided in a call to image-builder. These inputs must not be optional.

* Resolve conflicts.
./Dockerfile as default dockerfile path.

* Default to github repository name

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Co-authored-by: Kacper Małachowski <[email protected]>

.github/workflows/image-builder.yml

@@ -9,12 +9,12 @@ on:
         description: Name of the build image
         required: false
         type: string
-        default: test-infra/ginkgo
+        default: ${{ github.event.repository.name }}
       dockerfile:
         description: Path to the dockerfile used to build docker image
         required: false
         type: string
-        default: "images/ginkgo/Dockerfile"
+        default: "./Dockerfile"
       context:
         description: Build context to build container from
         required: false