Avoid recording RestClient observations twice

Prior to this commit, the fix for gh-32575 introduced cases where the
client observation would be stopped twice.

This commit ensures that `RestClient` observations are stopped only once
when the response is closed, or before throwing an unhanlded exception.

Fixes gh-33068

spring-web/src/main/java/org/springframework/web/client/DefaultRestClient.java

@@ -240,19 +240,16 @@ private <T> T readWithMessageConverters(ClientHttpResponse clientResponse, Runna
 					ResolvableType.forType(bodyType) + "] and content type [" + contentType + "]", cause);
 			if (observation != null) {
 				observation.error(restClientException);
+				observation.stop();
 			}
 			throw restClientException;
 		}
 		catch (RestClientException restClientException) {
 			if (observation != null) {
 				observation.error(restClientException);
-			}
-			throw restClientException;
-		}
-		finally {
-			if (observation != null) {
 				observation.stop();
 			}
+			throw restClientException;
 		}
 	}
 

spring-web/src/test/java/org/springframework/web/client/RestClientObservationTests.java

@@ -73,7 +73,6 @@ class RestClientObservationTests {
 
 	@BeforeEach
 	void setupEach() {
-
 		this.client = RestClient.builder()
 				.messageConverters(converters -> converters.add(0, this.converter))
 				.requestFactory(this.requestFactory)
@@ -267,6 +266,7 @@ private void mockResponseBody(String expectedBody, MediaType mediaType) throws E
 
 
 	private TestObservationRegistryAssert.TestObservationRegistryAssertReturningObservationContextAssert assertThatHttpObservation() {
+		TestObservationRegistryAssert.assertThat(this.observationRegistry).hasNumberOfObservationsWithNameEqualTo("http.client.requests",1);
 		return TestObservationRegistryAssert.assertThat(this.observationRegistry)
 				.hasObservationWithNameEqualTo("http.client.requests").that();
 	}