Use maven 3.8.4 version with enforcer plugin

Main pom.xml defined maven enforcer plugin, but the enforcer is actually not used. Use the enforcer across the sub-modules to make sure all the artifacts are built with same maven version.

Update: The enforcer plugin was already used in the sub modules but with 3.6.3 as requireMavenVersion. We need to run the build with only 3.8.4 as it doesn't work properly with 3.8.5.