ci: update mergify config for labelling PRs

When the configuration for Mergify itself gets updated, there is not
need to run the e2e tests.

It seems that the `(ci)` part of matching a title for ci/testing PRs
would match partial words like 'capacity'. This is not intended, so
rephrasing the regex and adding `e2e` as match too.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

.mergify.yml

@@ -321,9 +321,9 @@ pull_request_rules:
       label:
         add:
           - component/rbd
-  - name: title contains CI or testing
+  - name: title contains CI, testing or e2e
     conditions:
-      - "title~=(ci)|(testing): "
+      - "title~=(ci: )|(testing: )|(e2e)"
     actions:
       label:
         add:
@@ -364,3 +364,11 @@ pull_request_rules:
         add:
           - component/docs
           - ci/skip/e2e
+  - name: title contains Mergify
+    conditions:
+      - "title~=mergify"
+    actions:
+      label:
+        add:
+          - Repo activity
+          - ci/skip/e2e