Restrict "uri" KeyValue for client observations

Prior to this commit, the "uri" KeyValue for low cardinality metadata
would contain the entire uri template given to the HTTP client when
creating the request. This was a breaking change for existing metrics
dashboards, as previous support was removing the protocol, host and port
parts of the URI.
Indeed, this information is available in the "client.name" and
"http.uri" KayValue.

This commit parses and removes the protocol+host+port information from
the uri template for the "uri" KeyValue.

Fixes gh-29885

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultClientRequestObservationConventionTests.java

@@ -114,6 +114,14 @@ class DefaultClientRequestObservationConventionTests {
 		assertThat(this.observationConvention.getLowCardinalityKeyValues(context)).contains(KeyValue.of("uri", "/"));
 	}
 
+	@Test
+	void shouldOnlyConsiderPathForUriKeyValue() {
+		ClientRequestObservationContext context = createContext(ClientRequest.create(HttpMethod.GET, URI.create("https://example.org/resource/42")));
+		context.setUriTemplate("https://example.org/resource/{id}");
+		context.setRequest(context.getCarrier().build());
+		assertThat(this.observationConvention.getLowCardinalityKeyValues(context)).contains(KeyValue.of("uri", "/resource/{id}"));
+	}
+
 	private ClientRequestObservationContext createContext(ClientRequest.Builder request) {
 		ClientRequestObservationContext context = new ClientRequestObservationContext();
 		context.setCarrier(request);