Do not run content-provider build images job on doc changes

Add irrelevant-files patterns to content-provider-build-images-base job
to exclude documentation-only changes. This follows the same pattern
applied to EDPM jobs in commit c2f3dbd, ensuring content provider jobs
don't run unnecessarily on doc changes.

Assisted by: Claude Sonnet 4 <noreply@anthropic.com>

Signed-off-by: Amartya Sinha <amsinha@redhat.com>

Author: amartyasinha

zuul.d/edpm_build_images_content_provider.yaml

@@ -4,6 +4,11 @@
     parent: base-ci-framework
     nodeset: centos-stream-9
     abstract: true
+    irrelevant-files:
+      - ^CONTRIBUTING.md
+      - ^docs/*
+      - ^OWNERS*
+      - roles/.*/molecule/.*
     required-projects:
       - opendev.org/zuul/zuul-jobs
       - github.com/openstack-k8s-operators/edpm-image-builder