Android agent - HttpAttributesVisitor Not Invoked for Auto-Instrumented HTTP Calls

### **Describe the bug**
When using a custom `HttpAttributesVisitor` with the Elastic APM Android SDK, it never gets invoked for auto-instrumented HTTP requests. The default spans (`HTTP GET`, `HTTP POST`) appear in APM, but the custom visitor code (including any log statements) is never executed.

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### **To Reproduce**

1. Use this configuration (simplified example):
```kotlin
class ApmAttributesVisitor : HttpAttributesVisitor {
override fun visit(builder: AttributesBuilder, request: HttpRequest) {
Log.d("ApmAgentLogs", "Enter Visitor fun")
val uri = Uri.parse(request.url.toString())
val rawPath = uri.path ?: "/"
builder.put("http.route", rawPath)
}
}

val httpTraceConfig = HttpTraceConfiguration.builder()
.addHttpAttributesVisitor(ApmAttributesVisitor())
.build()

val instrumentationsConfig = InstrumentationConfiguration.builder()
.enableHttpTracing(true)
.build()

val elasticConfig = ElasticApmConfiguration.builder()
.setHttpTraceConfiguration(httpTraceConfig)
.setInstrumentationConfiguration(instrumentationsConfig)
.setServiceName("MyServiceName")
.build()

ElasticApmAgent.initialize(application, elasticConfig)
```

2. Make an OkHttp-based network call.
3. Observe that the APM UI captures spans named `HTTP GET` or `HTTP POST`, but your custom visitor’s logic is never called (no logs, no custom attributes).

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### **Expected behavior**
- The `HttpAttributesVisitor` should be invoked for each auto-instrumented HTTP request.
- Logs in `visit(...)` should appear in Logcat.
- Any custom attributes (e.g., `http.route`) should appear in the APM UI.

---

### **Debug logs**
I enabled debug logging for the agent but found no references to the custom visitor being invoked.