standard-tests.yaml: Rename to ci.yaml

In another attempt at making CI workflow naming more concise:
- Rename standard-tests.yaml to ci.yaml
    Currently the contents of this file covers everything CI-related
    that happens in the context workflows, so for the time being,
    naming it ci.yaml is just fitting. And it's going to be shorter
    in commit message summaries. Should a real need arise, we can
    always split the file up again.
  - Shorten names again, otherwise they don't fit into Forgejo's
    check-mark-popup. That should be self-explanatory in context:
    name:
      Default CI -> CI
    jobs.CI.name:
      Packaging test - All supported platforms -> Packaging test
Signed-off-by: Jan Lindemann <jan@janware.com>

.github/workflows/ci.yaml

@@ -0,0 +1,13 @@
+name: CI
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  push:
+    branches:
+      - master
+      - main
+      - released
+jobs:
+  CI:
+    name: Packaging test
+    uses: ci/workflows/.github/workflows/test-packaging.yaml@master-test