[ci] Fix infra pipeline image-pull — drop :5050 from infra-ci image URL

P366-P374 default workflow failed with exit 126 "image can't be pulled" — containerd
hosts.toml has a mirror entry for `registry.viktorbarzin.me` but NOT for
`registry.viktorbarzin.me:5050`, so pulls fell through to direct HTTPS on :5050
(which isn't exposed externally). Convention per infra/.claude/CLAUDE.md is the
no-port form; :5050 was an anomaly introduced by the 2026-04-15 CI perf overhaul.

build-cli/build-ci-image push paths still use :5050 and work fine — they go through
the buildx plugin (pod DNS, not node containerd). Only `image:` fields on a step
hit the broken path. Normalizing push URLs left for a follow-up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.woodpecker/default.yml

@@ -25,7 +25,7 @@ clone:
 
 steps:
   - name: apply
-    image: registry.viktorbarzin.me:5050/infra-ci:latest
+    image: registry.viktorbarzin.me/infra-ci:latest
     pull: true
     backend_options:
       kubernetes:

.woodpecker/drift-detection.yml

@@ -14,7 +14,7 @@ clone:
 
 steps:
   - name: detect-drift
-    image: registry.viktorbarzin.me:5050/infra-ci:latest
+    image: registry.viktorbarzin.me/infra-ci:latest
     pull: true
     backend_options:
       kubernetes: