Fix template preview (#3937)

# What this PR does

Fixes template preview URL

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Change plugin build to use new packages instead of deprecated grafana-toolkit @maskin25 ([#3837](https://github.com/grafana/oncall/pull/3837))
 
+### Fixed
+
+- Fix template preview by @vadimkerr ([#3937](https://github.com/grafana/oncall/pull/3937))
+
 ## v1.3.106 (2024-02-20)
 
 ### Added

grafana-plugin/src/models/alert_receive_channel/alert_receive_channel.helpers.ts

@@ -126,7 +126,7 @@ export class AlertReceiveChannelHelper {
     payload: { [key: string]: unknown }
   ) {
     return (
-      await onCallApi().POST('/alertgroups/{id}/preview_template/', {
+      await onCallApi().POST('/alert_receive_channels/{id}/preview_template/', {
         params: { path: { id } },
         body: { template_name, template_body, payload },
       })