Update Grafana dashboards and workflows for enhanced RPC metrics observability

Highlights:
- Refactor Prometheus queries in Grafana dashboards to include `kind="rpc"` for accurate RPC-based metric insights.
- Replace static durations (e.g., `5m`) with dynamic rate intervals (`$__rate_interval`) for consistency and better adaptability of panels.
- Synchronize titles and labels across dashboards to emphasize RPC context (e.g., "Request Rate" → "RPC Request Rate").
- Ensure metrics such as latencies, error rates, and overheads clearly distinguish RPC-specific data.
- Minor cleanup in `.github/workflows/docker-build.yml` to streamline arguments and remove unused lines.

Author: jorgecuesta

.github/workflows/docker-build.yml

@@ -27,7 +27,7 @@ jobs:
         uses: golangci/golangci-lint-action@v8
         with:
           version: v2.1
-          args: ./app/... ./cmd/... ./pkg/... --tests=false --timeout=5m
+          args: --timeout=5m
 
   go-fmt-check:
     name: Go Format Check (gofmt + goimports)
@@ -63,7 +63,6 @@ jobs:
             exit 1
           fi
 
-
   build-and-push:
     runs-on: ubuntu-latest
     permissions: