Change the default build-platforms to only build locallly

Now that we can support a matrix of size one out of the box, changing
the default configuraiton for multi-platform builds to only run
in-cluster.

Signed-off-by: arewm <arewm@users.noreply.github.com>

pipelines/docker-build-multi-platform-oci-ta/README.md

@@ -10,7 +10,7 @@ This pipeline is pushed as a Tekton bundle to [quay.io](https://quay.io/reposito
 |build-args| Array of --build-arg values ("arg=value" strings) for buildah| []| build-images:0.2:BUILD_ARGS|
 |build-args-file| Path to a file with build arguments for buildah, see https://www.mankier.com/1/buildah-build#--build-arg-file| | build-images:0.2:BUILD_ARGS_FILE|
 |build-image-index| Add built image into an OCI image index| true| build-image-index:0.1:ALWAYS_BUILD_INDEX|
-|build-platforms| List of platforms to build the container images on. The available set of values is determined by the configuration of the multi-platform-controller.| ['linux/x86_64', 'linux/arm64']| |
+|build-platforms| List of platforms to build the container images on. The available set of values is determined by the configuration of the multi-platform-controller.| ['linux/x86_64']| |
 |build-source-image| Build a source image.| false| |
 |dockerfile| Path to the Dockerfile inside the context specified by parameter path-context| Dockerfile| build-images:0.2:DOCKERFILE ; push-dockerfile:0.1:DOCKERFILE|
 |git-url| Source Repository URL| None| clone-repository:0.1:url|

pipelines/docker-build-multi-platform-oci-ta/patch.yaml

@@ -85,4 +85,3 @@
     type: array
     default:
       - "linux/x86_64"
-      - "linux/arm64"