workflows: Add back the checks for running test-kata-deploy

Commit 3c9ae7f made /test_kata_deploy run
against HEAD, but it also mistakenly removed all the checks that ensure
/test_kata_deploy only runs when explicitly called.

Mea culpa on this, and let's add the tests back.

Fixes: #3101

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

.github/workflows/kata-deploy-test.yaml

@@ -6,6 +6,11 @@ name: test-kata-deploy
 
 jobs:
   build-asset:
+    if: |
+      github.event.issue.pull_request
+      && github.event_name == 'issue_comment'
+      && github.event.action == 'created'
+      && startsWith(github.event.comment.body, '/test_kata_deploy')
     runs-on: ubuntu-latest
     strategy:
       matrix: