Alerting docs: clean up Cloud links (#83073)

* Use fixed `/docs/grafana-cloud/alerting-and-irm` URLs for cloud references

* Fix `docs/grafana-cloud/` data sources links

* Fix `docs/grafana-cloud/` Panel & Visualization links

* Fix `/docs/grafana-cloud/` link to Dashboard page

* Set root directory `docs/reference` for non-cloud pages

* Fix `admonition` cannot use a  `docs/reference` relative link

* Update `doc-validator`

https://github.com/grafana/technical-documentation/releases/tag/doc-validator%2Fv4.1.0

Signed-off-by: Jack Baldry <jack.baldry@grafana.com>

---------

Signed-off-by: Jack Baldry <jack.baldry@grafana.com>
Co-authored-by: Jack Baldry <jack.baldry@grafana.com>

.github/workflows/doc-validator.yml

@@ -7,7 +7,7 @@ jobs:
   doc-validator:
     runs-on: "ubuntu-latest"
     container:
-      image: "grafana/doc-validator:v4.0.0"
+      image: "grafana/doc-validator:v4.1.0"
     steps:
       - name: "Checkout code"
         uses: "actions/checkout@v4"