Pooled `ConnectionProvider` metrics

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| metric name | type | description
| reactor.netty.connection.provider.total.connections | Gauge | The number of all connections, active or idle.
See xref:observability.adoc#observability-metrics-total-connections[Total Connections]
| reactor.netty.connection.provider.active.connections | Gauge | The number of the connections that have been successfully acquired and are in active use.
See xref:observability.adoc#observability-metrics-active-connections[Active Connections]
| reactor.netty.connection.provider.max.connections | Gauge | The maximum number of active connections that are allowed.
See xref:observability.adoc#observability-metrics-max-connections[Max Connections]
| reactor.netty.connection.provider.idle.connections | Gauge | The number of the idle connections.
See xref:observability.adoc#observability-metrics-idle-connections[Idle Connections]
| reactor.netty.connection.provider.pending.connections | Gauge | The number of requests that are waiting for a connection.
See xref:observability.adoc#observability-metrics-pending-connections[Pending Connections]
| reactor.netty.connection.provider.pending.connections.time | Timer | Time spent in pending acquire a connection from the connection pool.
See xref:observability.adoc#observability-metrics-pending-connections-time[Pending Connections Time]
| reactor.netty.connection.provider.max.pending.connections | Gauge | The maximum number of requests that will be queued while waiting for a ready connection.
See xref:observability.adoc#observability-metrics-max-pending-connections[Max Pending Connections]
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