### What changes were proposed in this pull request?
Cleanup all Zinc standalone server code, and realated coniguration.
### Why are the changes needed?
- Zinc is the incremental compiler to speed up builds of compilation.
- The scala-maven-plugin is the mave plugin, which is used by Spark, one of the function is to integrate the Zinc to enable the incremental compiler.
- Since Spark v3.0.0 ([SPARK-28759](https://issues.apache.org/jira/browse/SPARK-28759)), the scala-maven-plugin is upgraded to v4.X, that means Zinc v0.3.13 standalone server is useless anymore.
However, we still download, install, start the standalone Zinc server. we should remove all zinc standalone server code, and all related configuration.
See more in [SPARK-34539](https://issues.apache.org/jira/projects/SPARK/issues/SPARK-34539) or the doc [Zinc standalone server is useless after scala-maven-plugin 4.x](https://docs.google.com/document/d/1u4kCHDx7KjVlHGerfmbcKSB0cZo6AD4cBdHSse-SBsM).
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Run any mvn build:
./build/mvn -DskipTests clean package -pl core
You could see the increamental compilation is still working, the stage of "scala-maven-plugin:4.3.0:compile (scala-compile-first)" with incremental compilation info, like:
```
[INFO] --- scala-maven-plugin:4.3.0:testCompile (scala-test-compile-first) spark-core_2.12 ---
[INFO] Using incremental compilation using Mixed compile order
[INFO] Compiler bridge file: /root/.sbt/1.0/zinc/org.scala-sbt/org.scala-sbt-compiler-bridge_2.12-1.3.1-bin_2.12.10__52.0-1.3.1_20191012T045515.jar
[INFO] compiler plugin: BasicArtifact(com.github.ghik,silencer-plugin_2.12.10,1.6.0,null)
[INFO] Compiling 303 Scala sources and 27 Java sources to /root/spark/core/target/scala-2.12/test-classes ...
```
Closes#31647 from Yikun/cleanup-zinc.
Authored-by: Yikun Jiang <yikunkero@gmail.com>
Signed-off-by: Sean Owen <srowen@gmail.com>
85b50d4258
