Refine Reactor field precomputing on native

This commit refines Reactor field precomputing on native
to only compute at build-time fields in the reactor.core
package, since doing so in reactor.netty has unwanted side
effects like Epoll always disabled.

Closes gh-31141

spring-core/src/main/java/org/springframework/aot/nativex/feature/PreComputeFieldFeature.java

@@ -38,7 +38,7 @@ class PreComputeFieldFeature implements Feature {
 			Pattern.compile(Pattern.quote("org.springframework.aot.AotDetector#inNativeImage")),
 			Pattern.compile(Pattern.quote("org.springframework.") + ".*#.*Present"),
 			Pattern.compile(Pattern.quote("org.springframework.") + ".*#.*PRESENT"),
-			Pattern.compile(Pattern.quote("reactor.") + ".*#.*Available"),
+			Pattern.compile(Pattern.quote("reactor.core.") + ".*#.*Available"),
 			Pattern.compile(Pattern.quote("org.apache.commons.logging.LogAdapter") + "#.*Present")
 	};