fix: use 409 when deleting destination/templates already in use (#4294)

Fixes #4291 

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit


- **New Features**
- Introduced a new method for handling 409 Conflict responses in the
HTTP responses, improving error messaging clarity.

- **Bug Fixes**
- Updated error handling to return conflict responses instead of
forbidden responses when certain delete operations fail due to resource
conflicts.
- Enhanced clarity in user membership responses by changing the error
message when a user is already part of an organization.

These changes improve user experience by providing clearer and more
accurate feedback on error conditions related to resource management.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

src/handler/http/request/alerts/destinations.rs

@@ -183,7 +183,7 @@ async fn list_destinations(
     ),
     responses(
         (status = 200, description = "Success",   content_type = "application/json", body = HttpResponse),
-        (status = 403, description = "Forbidden", content_type = "application/json", body = HttpResponse),
+        (status = 409, description = "Conflict", content_type = "application/json", body = HttpResponse),
         (status = 404, description = "NotFound",  content_type = "application/json", body = HttpResponse),
         (status = 500, description = "Failure",   content_type = "application/json", body = HttpResponse),
     )
@@ -194,7 +194,7 @@ async fn delete_destination(path: web::Path<(String, String)>) -> Result<HttpRes
     match destinations::delete(&org_id, &name).await {
         Ok(_) => Ok(MetaHttpResponse::ok("Alert destination deleted")),
         Err(e) => match e {
-            (http::StatusCode::FORBIDDEN, e) => Ok(MetaHttpResponse::forbidden(e)),
+            (http::StatusCode::CONFLICT, e) => Ok(MetaHttpResponse::conflict(e)),
             (http::StatusCode::NOT_FOUND, e) => Ok(MetaHttpResponse::not_found(e)),
             (_, e) => Ok(MetaHttpResponse::internal_error(e)),
         },

src/handler/http/request/alerts/templates.rs

@@ -174,7 +174,7 @@ async fn list_templates(path: web::Path<String>, _req: HttpRequest) -> Result<Ht
     ),
     responses(
         (status = 200, description = "Success",   content_type = "application/json", body = HttpResponse),
-        (status = 403, description = "Forbidden", content_type = "application/json", body = HttpResponse),
+        (status = 409, description = "Conflict", content_type = "application/json", body = HttpResponse),
         (status = 404, description = "NotFound",  content_type = "application/json", body = HttpResponse),
         (status = 500, description = "Failure",   content_type = "application/json", body = HttpResponse),
     )
@@ -185,7 +185,7 @@ async fn delete_template(path: web::Path<(String, String)>) -> Result<HttpRespon
     match templates::delete(&org_id, &name).await {
         Ok(_) => Ok(MetaHttpResponse::ok("Alert template deleted")),
         Err(e) => match e {
-            (http::StatusCode::FORBIDDEN, e) => Ok(MetaHttpResponse::forbidden(e)),
+            (http::StatusCode::CONFLICT, e) => Ok(MetaHttpResponse::conflict(e)),
             (http::StatusCode::NOT_FOUND, e) => Ok(MetaHttpResponse::not_found(e)),
             (_, e) => Ok(MetaHttpResponse::internal_error(e)),
         },

src/handler/http/request/dashboards/reports.rs

@@ -202,7 +202,7 @@ async fn delete_report(path: web::Path<(String, String)>) -> Result<HttpResponse
     match reports::delete(&org_id, &name).await {
         Ok(_) => Ok(MetaHttpResponse::ok("Report deleted")),
         Err(e) => match e {
-            (http::StatusCode::FORBIDDEN, e) => Ok(MetaHttpResponse::forbidden(e)),
+            (http::StatusCode::CONFLICT, e) => Ok(MetaHttpResponse::conflict(e)),
             (http::StatusCode::NOT_FOUND, e) => Ok(MetaHttpResponse::not_found(e)),
             (_, e) => Ok(MetaHttpResponse::internal_error(e)),
         },