.github/workflows: reviewing depaware.txt is unnecessary (#16990)

Apparently, #16989 introduced a bug in request-dataplane-review.yml:

> you may only define one of `paths` and `paths-ignore` for a single event

Related #16372
Updates #cleanup

Signed-off-by: Simon Law <sfllaw@tailscale.com>

.github/workflows/request-dataplane-review.yml

@@ -8,8 +8,7 @@ on:
       - ".github/workflows/request-dataplane-review.yml"
       - "**/*derp*"
       - "**/derp*/**"
-    paths-ignore:
-      - "**/depaware.txt"
+      - "!**/depaware.txt"
 
 jobs:
   request-dataplane-review: