Add contextualName to HTTP Observations

This commit ensures that all HTTP `ObservationConvention`
implementations provide a consistent contextual name for observations.
This name should be like "http get" where only the HTTP verb changes
depending on the request.

Fixes gh-29231

spring-web/src/main/java/org/springframework/http/client/observation/DefaultClientHttpObservationConvention.java

@@ -69,6 +69,11 @@ public class DefaultClientHttpObservationConvention implements ClientHttpObserva
 		return this.name;
 	}
 
+	@Override
+	public String getContextualName(ClientHttpObservationContext context) {
+		return "http " + context.getCarrier().getMethod().name().toLowerCase();
+	}
+
 	@Override
 	public KeyValues getLowCardinalityKeyValues(ClientHttpObservationContext context) {
 		return KeyValues.of(uri(context), method(context), status(context), exception(context), outcome(context));

spring-web/src/main/java/org/springframework/web/observation/DefaultHttpRequestsObservationConvention.java

@@ -70,6 +70,11 @@ public class DefaultHttpRequestsObservationConvention implements HttpRequestsObs
 		return this.name;
 	}
 
+	@Override
+	public String getContextualName(HttpRequestsObservationContext context) {
+		return "http " + context.getCarrier().getMethod().toLowerCase();
+	}
+
 	@Override
 	public KeyValues getLowCardinalityKeyValues(HttpRequestsObservationContext context) {
 		return KeyValues.of(method(context), uri(context), status(context), exception(context), outcome(context));

spring-web/src/main/java/org/springframework/web/observation/reactive/DefaultHttpRequestsObservationConvention.java

@@ -73,6 +73,11 @@ public class DefaultHttpRequestsObservationConvention implements HttpRequestsObs
 		return this.name;
 	}
 
+	@Override
+	public String getContextualName(HttpRequestsObservationContext context) {
+		return "http " + context.getCarrier().getMethod().name().toLowerCase();
+	}
+
 	@Override
 	public KeyValues getLowCardinalityKeyValues(HttpRequestsObservationContext context) {
 		return KeyValues.of(method(context), uri(context), status(context), exception(context), outcome(context));