fix(prometheus, syslog): a target or pattern pauses with a Pause/Resume button, not an "on" tick box in its form (#6419)

Monitors, schedules and maintenance plans already pause with a
Pause/Resume button and say "Paused" where they're listed. Prometheus
targets and syslog patterns only had a tick box inside the edit form,
so a target refused by its endpoint couldn't be stopped from its page.

- Both get a Pause/Resume button (target page and list; patterns list)
  posting to /toggle, recorded in the audit log, and a Paused badge.
- The forms lose the tick box. A new one starts running; an edit keeps
  whether it is paused.
- A target's "off" state is now "paused", in its pages and MCP tools.
  A resumed target reads "not scraped yet" until its next scrape, and its
  counter rates start over.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugins/prometheus/templates/prometheus/form.html

@@ -51,9 +51,6 @@
       </div>
     </div>
     <div style="display:flex;gap:1.5rem;flex-wrap:wrap;margin-bottom:0.9rem;">
-      <label style="display:flex;gap:0.5rem;align-items:center;cursor:pointer;">
-        <input type="checkbox" name="enabled" value="on"{% if v.enabled %} checked{% endif %}> Scrape this target
-      </label>
       <label style="display:flex;gap:0.5rem;align-items:center;cursor:pointer;">
         <input type="checkbox" name="verify_tls" value="on"{% if v.verify_tls %} checked{% endif %}> Check its HTTPS certificate
       </label>