similar to #24314, this moves drone cron pipelines to (GitHub) Actions.
As these are mostly compatible with Gitea Actions, when we start to
dogfood, these will already be migrated.
I also removed the discord notify pipeline, as it hasn't been working
for several months.
Move drone cron pipelines to (GitHub) Actions. As these are mostly
compatible with Gitea Actions, when we start to dogfood, these will
already be migrated.