feat(grafana): add events dashboard (#8725)

* feat(grafana): add events dashboard

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): tolerate evolving event schemas

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): address events dashboard review

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): restore events dashboard panels

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): bound events dashboard queries

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): include historical event catalogs

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): preserve events drill-down context

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): correct events lifecycle outcomes

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): handle empty event type ranges

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): scope event catalogs to submissions

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): handle empty events dashboard

Signed-off-by: WenyXu <wenymedia@gmail.com>

* fix(grafana): refresh event schema variables

Signed-off-by: WenyXu <wenymedia@gmail.com>

---------

Signed-off-by: WenyXu <wenymedia@gmail.com>

grafana/README.md

@@ -12,6 +12,10 @@ We highly recommend using the self-monitoring feature provided by [GreptimeDB Op
 
   - `dashboards/metrics/standalone/dashboard.json`: The Grafana dashboard for the standalone GreptimeDB instance. **It's generated from the `cluster/dashboard.json` by removing the instance filter through the `make dashboards` command**. Read the [dashboard.md](./dashboards/metrics/standalone/dashboard.md) for more details.
 
+- **Events Dashboards**
+
+  - `dashboards/events/dashboard.json`: The Grafana dashboard for procedure and maintenance events. It includes DDL, Batch GC, WAL Prune, Repartition, and Region Migration views.
+
 - **Logs Dashboard**
 
   The `dashboards/logs/dashboard.json` provides a comprehensive Grafana dashboard for visualizing GreptimeDB logs. To utilize this dashboard effectively, you need to collect logs in JSON format from your GreptimeDB instances and store them in a dedicated GreptimeDB instance.
@@ -52,6 +56,7 @@ For easier dashboard maintenance, we utilize the [`dac`](https://github.com/zyy1
 - `dashboards/metrics/cluster/dashboard.yaml`: The intermediate dashboard file for the GreptimeDB cluster.
 - `dashboards/metrics/standalone/dashboard.yaml`: The intermediate dashboard file for standalone GreptimeDB instances.
 
+
 ## Data Sources
 
 The following data sources are used to fetch metrics and logs: