Optimize Jackson resource management in codecs

Prior to this commit, references to `JsonGenerator` and
`ByteArrayBuilder` were not closed/released within codecs calls.
This prevents Jackson from reusing more efficiently shared memory
resources.

This commit properly closes/releases Jackson resources in Spring MVC,
Spring WebFlux and Spring Messaging codecs.
A benchmark on WebFlux codecs (in both single value/streaming mode)
shows significant throughput and allocation improvements for small
payloads.

Closes gh-25910

spring-web/src/test/resources/log4j2-test.xml

@@ -6,7 +6,7 @@
 		</Console>
 	</Appenders>
 	<Loggers>
-		<Logger name="org.springframework.web" level="debug" />
+		<Logger name="org.springframework.web" level="warn" />
 		<Logger name="org.springframework.beans" level="warn" />
 		<Logger name="org.springframework.binding" level="warn" />
 		<Logger name="org.springframework.http" level="warn" />