Update Maven wrapper to 3.9.15

Bump Maven Wrapper version from 3.9.9 to 3.9.15 and switch distributionUrl from the aliyun mirror to Maven Central (repo1.maven.org). Updates .mvn/wrapper/maven-wrapper.properties so the wrapper downloads the correct binary.

Author: mercyblitz

.mvn/wrapper/maven-wrapper.properties

@@ -1,3 +1,3 @@
 wrapperVersion=3.3.4
 distributionType=only-script
-distributionUrl=https://maven.aliyun.com/repository/public/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip
+distributionUrl=https://repo1.maven.org/maven2/org/apache/maven/apache-maven/3.9.15/apache-maven-3.9.15-bin.zip