v-m: Quit scraping Jenkins with blackbox_exporter

I was doing this to monitor Jenkins's certificate, but since that's
managed by _cert-manager_, there's really practically no risk of it
expiring without warning anymore.  Since Jenkins is already being
scraped directly, having this extra check just gernerates extra
notifications when there is an issue without adding any real value.

victoria-metrics/scrape.yml

@@ -60,7 +60,6 @@ scrape_configs:
     - https://nextcloud.pyrocufflink.net/
     - https://bitwarden.pyrocufflink.blue/
     - https://git.pyrocufflink.blue/
-    - https://jenkins.pyrocufflink.blue/login
     - https://tabitha.biz/
     - https://dustinandtabitha.com/
     - https://hatchlearningcenter.org/