fix: use Http2ClientConfiguration.PREFIX for ServiceHttp2ClientConfiguration

The `@ConfigurationProperties` annotation on `ServiceHttp2ClientConfiguration`
was referencing `WebSocketCompressionConfiguration.PREFIX` ("ws.compression")
instead of `Http2ClientConfiguration.PREFIX` ("http2"), likely a copy-paste
error from the adjacent `ServiceWebSocketCompressionConfiguration` class.

This caused the nested HTTP/2 client configuration for per-service clients
(`micronaut.http.services.<name>.http2.*`) to bind under the wrong property
path and collide with the WebSocket compression configuration prefix.

Fixes #12620

Author: Sai

http-client-core/src/main/java/io/micronaut/http/client/ServiceHttpClientConfiguration.java

@@ -321,7 +321,7 @@ public static class ServiceWebSocketCompressionConfiguration extends WebSocketCo
     /**
      * The service HTTP/2 configuration.
      */
-    @ConfigurationProperties(WebSocketCompressionConfiguration.PREFIX)
+    @ConfigurationProperties(Http2ClientConfiguration.PREFIX)
     public static class ServiceHttp2ClientConfiguration extends Http2ClientConfiguration {
     }