Alerting: Add MQTT notifications receiver

[alexander-akhmetov]

I also updated the Grafana version used for running the tests from 11.0.0 to 11.5.0.

---

Adds support for MQTT notifications receiver.

• PR to Grafana: Alerting: Add MQTT notifications receiver grafana#91487
• PR to alerting: Add MQTT receiver alerting#227

Example:

resource "grafana_contact_point" "mqtt" {
  name = "MQTT receiver"

  mqtt {
    broker_url     = "tcp://localhost:1883"
    client_id      = "grafana"
    topic          = "grafana/alerts"
    message_format = "json"
    username       = "user"
    password       = "password123"
    qos            = 1
    retain         = true
    tls_config {
      insecure_skip_verify = true
      ca_certificate       = "ca_cert"
      client_certificate   = "client_cert"
      client_key           = "client_key"
    }
  }
}

[github-actions]

In order to lower resource usage and have a faster runtime, PRs will not run Cloud tests automatically.
To do so, a Grafana Labs employee must trigger the cloud acceptance tests workflow manually.

[alexander-akhmetov]

make linkcheck was complaining:

Start checking at 2025-02-02 14:31:59+000

URL        `https://jqlang.github.io/jq/'
Parent URL file:///home/runner/work/terraform-provider-grafana/terraform-provider-grafana/docs/index.md, line 289, col 143
Real URL   https://jqlang.org/
Check time 0.455 seconds
Size       3KB
Warning    [http-redirected] Redirected to `https://jqlang.org/'
           status: 301 Moved Permanently.
Result     Valid: 200 OK