[PROXYSQL] add prometheus metrics to the chart, need to add port to rest-api - 6070 to pod

[allanian]

Hello, can you help me with that.
So, after that change, we can just create a podscrape and its will work.
From doc:

ProxySQL 2.1+ includes a built in Prometheus exporter. This exporter lets you expose and consume relevant ProxySQL metrics through a friendly interface.

Admin variables
admin-restapi_enabled:
Description: Enable or disables the metrics endpoint.
Default value: false
admin-restapi_port:
Description: Port on which metrics endpoint is going to be exposed.
Default value: 6070
admin-prometheus_memory_metrics_interval:
Description: Internal interval at which memory metrics are going to be collected.
Default value: 61