[release-20.0] Remove unnecessary Docker build workflows (#16196) (#16202)

Co-authored-by: vitess-bot[bot] <108069721+vitess-bot[bot]@users.noreply.github.com>

Author: vitess-bot[bot]

.github/workflows/docker_build_images.yml

@@ -1,10 +1,10 @@
-name: Docker Build Images (v20+)
+name: Docker Build Images
 on:
   push:
     branches:
       - main
     tags:
-      - 'v[2-9][0-9]*.*' # run only on tags greater or equal to v20.0.0
+      - 'v[2-9][0-9]*.*' # run only on tags greater or equal to v20.0.0 where this new way of building docker image was changed
 
 concurrency:
   group: format('{0}-{1}', ${{ github.ref }}, 'Docker Build Images (v20+)')