Configure rsyslog for logs export using the spec (#11338)

- Work on https://github.com/neondatabase/cloud/issues/24896
- Cplane part https://github.com/neondatabase/cloud/pull/26808

Instead of reconfiguring rsyslog via an API endpoint [we have
agreed](https://neondb.slack.com/archives/C04DGM6SMTM/p1743513810964509?thread_ts=1743170369.865859&cid=C04DGM6SMTM)
to have a new `logs_export_host` field as part of the compute spec.

---------

Co-authored-by: Tristan Partin <tristan@neon.tech>

libs/compute_api/src/requests.rs

@@ -30,9 +30,3 @@ pub struct SetRoleGrantsRequest {
     pub privileges: Vec<Privilege>,
     pub role: PgIdent,
 }
-
-/// Request of the /configure_telemetry API
-#[derive(Debug, Deserialize, Serialize)]
-pub struct ConfigureTelemetryRequest {
-    pub logs_export_host: Option<String>,
-}

libs/compute_api/src/spec.rs

@@ -168,6 +168,10 @@ pub struct ComputeSpec {
     /// Extensions should be present in shared_preload_libraries
     #[serde(default)]
     pub audit_log_level: ComputeAudit,
+
+    /// Hostname and the port of the otel collector. Leave empty to disable Postgres logs forwarding.
+    /// Example: config-shy-breeze-123-collector-monitoring.neon-telemetry.svc.cluster.local:10514
+    pub logs_export_host: Option<String>,
 }
 
 /// Feature flag to signal `compute_ctl` to enable certain experimental functionality.
@@ -179,9 +183,6 @@ pub enum ComputeFeature {
     /// track short-lived connections as user activity.
     ActivityMonitorExperimental,
 
-    /// Allow to configure rsyslog for Postgres logs export
-    PostgresLogsExport,
-
     /// This is a special feature flag that is used to represent unknown feature flags.
     /// Basically all unknown to enum flags are represented as this one. See unit test
     /// `parse_unknown_features()` for more details.