Clean HTTP response headers after decompression in JDK client

Prior to this commit, gh-35225 introduced HTTP response body
decompression support for "gzip" and "deflate" encodings for the
`JdkClientHttpRequestFactory`.

While body decompression works, the client keeps the "Content-Encoding"
and "Content-Length" response headers intact, which misleads further
response handling: the body size has changed and it is not compressed
anymore.

This commit ensures that the relevant response headers are removed from
the HTTP response after decompression.

Fixes gh-35668

spring-web/src/test/java/org/springframework/http/client/AbstractMockWebServerTests.java

@@ -136,6 +136,7 @@ public abstract class AbstractMockWebServerTests {
 							.body(buffer)
 							.code(200);
 					builder.setHeader(HttpHeaders.CONTENT_ENCODING, encoding);
+					builder.setHeader(HttpHeaders.CONTENT_LENGTH, buffer.size());
 					return builder.build();
 				}
 				return new MockResponse.Builder().code(404).build();

spring-web/src/test/java/org/springframework/http/client/JdkClientHttpRequestFactoryTests.java

@@ -135,7 +135,9 @@ class JdkClientHttpRequestFactoryTests extends AbstractHttpRequestFactoryTests {
 		try (ClientHttpResponse response = request.execute()) {
 			assertThat(response.getStatusCode()).as("Invalid response status").isEqualTo(HttpStatus.OK);
 			assertThat(response.getHeaders().getFirst("Content-Encoding"))
-					.as("Invalid content encoding").isEqualTo("gzip");
+					.as("Content Encoding should be removed").isNull();
+			assertThat(response.getHeaders().getFirst("Content-Length"))
+					.as("Content-Length should be removed").isNull();
 			assertThat(response.getBody()).as("Invalid request body").hasContent("Payload to compress");
 		}
 	}
@@ -150,7 +152,9 @@ class JdkClientHttpRequestFactoryTests extends AbstractHttpRequestFactoryTests {
 		try (ClientHttpResponse response = request.execute()) {
 			assertThat(response.getStatusCode()).as("Invalid response status").isEqualTo(HttpStatus.OK);
 			assertThat(response.getHeaders().getFirst("Content-Encoding"))
-					.as("Invalid content encoding").isEqualTo("deflate");
+					.as("Content Encoding should be removed").isNull();
+			assertThat(response.getHeaders().getFirst("Content-Length"))
+					.as("Content-Length should be removed").isNull();
 			assertThat(response.getBody()).as("Invalid request body").hasContent("Payload to compress");
 		}
 	}