PIP-222: Add CommandPartitionedTopicMetadata metrics

### Motivation

Currently, there's no way to track CommandPartitionedTopicMetadata requests. There's no metrics that indicate that a broker is handling CommandPartitionedTopicMetadata requests.

[Misconfigured]( https://github.com/apache/pulsar/issues/18243#:~:text=One%20example%20of,a%20Pulsar%20client. ) clients might flood brokers with CommandPartitionedTopicMetadata requests and cause high CPU consumption.

### Goal

1. Provide `pulsar_broker_command_execution_latency` metric
2. Provide `pulsar_broker_command_execution_failed` metric

### API Changes

_No response_

### Implementation

1. Initialize a `Histogram` instance in [ServerCnx.java](https://github.com/apache/pulsar/blob/master/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/ServerCnx.java) to record the command execution latency
```
private static final Histogram COMMAND_EXECUTION_LATENCY = Histogram
.build("pulsar_broker_command_execution_latency", "-")
.unit("ms")
.labelNames("command")
.buckets(1, 10, 50, 100, 200, 500, 1000, 2000)
.register();
```
The instance has the following labels:
a. cluster: The name of the cluster
b. command: The name of the command

2. Initialize a `Counter` instance in [ServerCnx.java](https://github.com/apache/pulsar/blob/master/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/ServerCnx.java) to record the command execution failed ops
```
private static final Counter COMMAND_EXECUTION_FAILED = Counter
.build("pulsar_broker_command_execution_failed", "-")
.labelNames("command", "code")
.register();
```
The instance has the following labels:
a. cluster: The name of the cluster
b. command: The name of the command
c. code: The command execution failed reason, see [ServerError](https://github.com/apache/pulsar/blob/67d9d63882a7814077646ace80a387f58600f20f/pulsar-common/src/main/proto/PulsarApi.proto#L193-L231)

### Alternatives

_No response_

### Anything else?

Related issue link: https://github.com/apache/pulsar/issues/18243