.gitignore: Ignore ci-cleanup.sh

The ci-cleanup file gets created in ci-automation/ to remove any
leftovers when a build gets stopped. Since it is in the git tree, git
status sees untracked files which is a bit confusing.
Ignore the ci-cleanup file.

Author: pothos

.gitignore

@@ -15,6 +15,7 @@
 # SDK container env passing helpers
 sdk_container/.env
 sdk_container/.sdkenv
+ci-cleanup.sh
 
 # build cache / artefacts directories
 __build__/