Feature/mariadb galera monitoring

[ljluestc]

What this PR does / why we need it:

Feature: MariaDB Galera Cluster Status Monitoring

This PR addresses issue #20755 by adding support for monitoring MariaDB Galera cluster status. It registers the standard Galera status variables as metrics in the Cloudpods monitoring system, enabling alerting and dashboards for cluster health. It also updates the Hostman service to support configuring Telegraf to collect these metrics from MySQL/MariaDB instances.

Implementation Details

1. pkg/monitor/dbinit/measurements/mysql.go:
Registered standard Galera status variables to mysql measurement definition:

		{
			"wsrep_cluster_size", "wsrep_cluster_size", monitor.METRIC_UNIT_COUNT,
		},
		{
			"wsrep_cluster_status", "wsrep_cluster_status", monitor.METRIC_UNIT_NULL,
		},
		{
			"wsrep_ready", "wsrep_ready", monitor.METRIC_UNIT_NULL,
		},
		{
			"wsrep_connected", "wsrep_connected", monitor.METRIC_UNIT_NULL,
		},

2. pkg/monitor/dbinit/measurements/metrics.csv:

• Updated to include the new wsrep metrics keys.

3. pkg/hostman/options/options.go:

• Added TelegrafMysqlServers option to SHostBaseOptions to allow configuring MySQL connection strings for Telegraf.

4. pkg/hostman/hostinfo/hostinfo.go:

• Updated OnCatalogChanged to read TelegrafMysqlServers and configure the mysql input for Telegraf, specifically requesting wsrep string fields.

5. pkg/hostman/system_service/telegraf.go:

• Implemented generation of [[inputs.mysql]] configuration block in telegraf.conf.

Does this PR need to be backport to the previous release branch?:

NONE

Verification

1. pkg/monitor/dbinit/measurements/mysql_test.go:
Added unit test to verify metric presence:

package measurements

import (
	"testing"
)

func TestMysqlMetrics(t *testing.T) {
	metrics := map[string]bool{
		"wsrep_cluster_size":    false,
		"wsrep_cluster_status":  false,
		"wsrep_ready":           false,
		"wsrep_connected":       false,
	}

	for _, m := range mysql.Metrics {
		if _, ok := metrics[m.Name]; ok {
			metrics[m.Name] = true
		}
	}

	for name, found := range metrics {
		if !found {
			t.Errorf("metric %s not found in mysql definitions", name)
		}
	}
}

Automated Tests:
Run the verification test:

go test -v -run TestMysqlMetrics ./pkg/monitor/dbinit/measurements/

Output:

=== RUN   TestMysqlMetrics
--- PASS: TestMysqlMetrics (0.00s)
PASS
ok  	yunion.io/x/onecloud/pkg/monitor/dbinit/measurements	0.002s

2. Hostman Telegraf Configuration Verification:
Verified that telegraf.conf is correctly generated with [[inputs.mysql]] block when TelegrafMysqlServers is configured.