[SPARK-21592][BUILD] Skip maven-compiler-plugin main and test compilations in Maven build

`scala-maven-plugin` in `incremental` mode compiles `Scala` and `Java` classes. There is no need to execute `maven-compiler-plugin` goals to compile (in fact recompile) `Java`.

This change reduces compilation time (over 10% on my machine).

Author: Grzegorz Slowikowski <gslowikowski@gmail.com>

Closes #18750 from gslowikowski/remove-redundant-compilation-from-maven.