apacheGH-41983: [Dev] Run issue labeling bot only when opening an iss…

…ue (not editing) (apache#41986)

### Rationale for this change

Currently the bot will remove manually added Component labels, because at that point you are editing the issue and the workflow is run again, reinstating the labels in the "Components" section in the top post created by the issue form.

Therefore, restrict this bot to only run when the issue is "opened"

* GitHub Issue: apache#41983

Authored-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Signed-off-by: Jacob Wujciak-Jens <jacob@wujciak.de>

.github/workflows/issue_bot.yml

@@ -21,7 +21,6 @@ on:
   issues:
     types:
       - opened
-      - edited
 
 permissions:
   contents: read