docs(rq): remove defunct --sentry-dsn CLI flag (#17937)

The `--sentry-dsn` option has been fully removed from RQ. The previous
docs showed it in the worker startup command with a comment `# only
necessary for RQ < 1.0`, which was misleading — the flag doesn't exist
at all in current RQ releases (not listed in [official RQ worker
args](https://python-rq.org/docs/workers/)).

This also fixes the circular reference loop:
`python-rq.org/patterns/sentry/` now just redirects back to this page,
pointing users at a flag that no longer exists.

**Changes:**
- Removed `--sentry-dsn` line from the worker startup command
- Updated the `## The --sentry-dsn CLI option` section to clearly state
the flag has been removed

Reported via Sentry User Feedback. Action taken on behalf of Rahul
Chhabria.

---
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Co-authored-by: sentry-junior[bot] <264270552+sentry-junior[bot]@users.noreply.github.com>
Co-authored-by: Rahul Chhabria <rahul.chhabria@sentry.io>
Co-authored-by: Johannes Daxböck <johannes.daxboeck@sentry.io>

Author: 3 people

docs/platforms/python/integrations/rq/index.mdx

@@ -64,8 +64,7 @@ Start your worker with:
 
 ```shell
 rq worker \
-    -c mysettings \  # module name of mysettings.py
-    --sentry-dsn="___PUBLIC_DSN___"  # only necessary for RQ < 1.0
+    -c mysettings  # module name of mysettings.py
 ```
 
 The integration will automatically report errors from all RQ jobs.
@@ -194,9 +193,7 @@ It takes a couple of moments for the data to appear in [sentry.io](https://sentr
 
 ## The `--sentry-dsn` CLI option
 
-Passing `--sentry-dsn=""` to RQ forcibly disables [RQ's shortcut for using Sentry](https://python-rq.org/patterns/sentry/). For RQ versions before 1.0 this is necessary to avoid conflicts, because back then RQ would attempt to use the `raven` package instead of this SDK. Since RQ 1.0 it's possible to use this CLI option and the associated RQ settings for initializing the SDK.
-
-We still recommend against using those shortcuts because it would be harder to provide options to the SDK at a later point. See [the GitHub issue about RQ's Sentry integration](https://github.com/rq/rq/issues/1003) for discussion.
+The `--sentry-dsn` CLI option has been removed from RQ. Initialize the Sentry SDK directly in your worker settings file (e.g. `mysettings.py`) as shown above.
 
 ## Supported Versions