* apk-tools passes the directories it triggers on as arguments to the
  trigger script. Use them to only run the relevant parts of the
  triggers.
* Remove "|| :" from commands, as we run the script without "set -e", it
  won't fail if a single command fails. Put explicit "exit 0" at the end
  to ensure this even if the last command beforehand failed.
* Print messages for each action so we know what is happening.

Part-of: !6346
[ci:skip-build]: already built successfully in CI