chore(build): remove comment from .mvn/maven.config for Maven 3.8 compatibility (#14609)

Support for '#' comments in .mvn/maven.config was introduced in Apache
Maven 3.9.0 (MNG-7682). Prior versions of Maven (such as 3.8.x) and IDE
Maven parsers split the entire file on whitespace and reject '#' comment
tokens with: Unable to parse maven.config: Unrecognized maven.config
entries: [#, TODO:, ...]

Remove the comment line from .mvn/maven.config so that it parses cleanly
across both Maven 3.8.x and 3.9+.

Author: sakthivelmanii

.mvn/maven.config

@@ -1,3 +1,2 @@
-# TODO: Remove this file once org.codehaus.mojo:flatten-maven-plugin is upgraded to 1.8.0+
 -Daether.remoteRepositoryFilter.prefixes=false
 -Daether.remoteRepositoryFilter.groupId=false