Add timestamp to kaniko builds (#11923)

The build steps at the start of CI takes about 2 minutes; now that we
have greatly reduced the overall duration, this is not an insignificant
impact.

Add timestamps to the build process to see measure which steps of the
image build take the most time.

.gitlab-ci/build.yml

@@ -25,6 +25,7 @@
                        --label 'git-branch'=$CI_COMMIT_REF_SLUG
                        --label 'git-tag=$CI_COMMIT_TAG'
                        --destination $PIPELINE_IMAGE
+                       --log-timestamp=true
 
 pipeline-image:
   extends: .build-container