fix(source opentelemetry): log error

If the HTTP opentelemetry source fails to build it is currently
silently ignored, without logging any info to the 'user'. The only
indication you have that something is wrong is that the log line about
the http listener starting is _not_ there.

With this change the error condition is logged the same way the gRPC
error is logged.

Before:

```
$ vector -c vector-otel.yaml
...
2026-02-23T09:15:50.053251Z  INFO vector: Vector has started. debug="false" version="0.52.0" arch="aarch64" revision="ca5bf26 2025-12-16 14:56:07.290167996"
2026-02-23T09:15:50.053468Z  INFO source{component_kind="source" component_id=otel component_type=opentelemetry}: vector::sources::util::grpc: Building gRPC server. address=127.0.0.1:4317
```

now:

```
$ target/debug/vector --config vector-otel.yaml
2026-02-23T09:16:49.397436Z  INFO vector: Vector has started. debug="true" version="0.54.0" arch="aarch64" revision=""
2026-02-23T09:16:49.398497Z  INFO source{component_kind="source" component_id=otel component_type=opentelemetry}: vector::sources::util::grpc: Building gRPC server. address=127.0.0.1:4317
2026-02-23T09:16:49.400243Z ERROR source{component_kind="source" component_id=otel component_type=opentelemetry}: vector::sources::opentelemetry::config: Source future failed. error=TCP bind failed: Address family not supported by protocol family (os error 47)
```

Author: fbs

src/sources/opentelemetry/config.rs

@@ -257,7 +257,10 @@ impl SourceConfig for OpentelemetryConfig {
             filters,
             cx.shutdown,
             self.http.keepalive.clone(),
-        );
+        )
+        .map_err(|error| {
+            error!(message = "Source future failed.", %error);
+        });
 
         Ok(join(grpc_source, http_source).map(|_| Ok(())).boxed())
     }