As a use, I want to add URI label to http_requests_total metric in prometheus plugin

### Description

The current prometheus plugin provides `http_requests_total` metric to track the total number of client requests. However, it lacks the ability to track requests by URI, which is crucial for monitoring traffic patterns and identifying potential bottlenecks at the endpoint level.

### Why

Currently, `http_requests_total` is defined as a simple gauge without labels:

```
metrics.requests = prometheus:gauge("http_requests_total"
```

This would allow users to:
- Track request counts per endpoint
- Set up alerts based on endpoint-specific traffic patterns
- Better understand traffic distribution across different APIs

In addition, it will be consistent with other metrics like `http_status` which already includes URI information

Start by locating the Prometheus plugin code that defines the http_requests_total metric as a gauge. Compare it with the existing http_status metric's URI information, then verify that request totals can be tracked per URI and that the metric remains usable for endpoint-specific monitoring.

Written by the indexing model from the issue text.