Function extract_grpc_method_name

pub fn extract_grpc_method_name(path: &str) -> &str

Extracts the gRPC method name from a request URI path.

gRPC paths have the form /{package}.{Service}/{Method} — the first segment always contains a dot. Non-gRPC requests (health checks, bot probes, etc.) return "non_grpc" to prevent unbounded label cardinality.