Build: Stop double generating buildSrc pom

[nik9000]

When we added the java-gradle-plugin to buildSrc it added a second
task to generate the pom that duplicates the publishing work that we
configure in BuildPlugin. Not only does it dupliciate the pom, it
creates a pom that is missing things like name and description which
are required for publishing to maven central.

This change disables the duplicate pom generation.

[elasticmachine]

Pinging @elastic/es-core-infra

[jasontedor]

LGTM.

[jasontedor]

My testing of applying this patch to 6.4:

[jason@totoro elasticsearch-6.x]$ git log --pretty=oneline | head -2
be89427ccb3acaa522870492cfc014d71ceea58a Build: Stop double generating buildSrc pom
4c2fbcf4c3481b944db28705dc3d346aada6a97a Only enforce password hashing check if FIPS enabled (#32383)
[jason@totoro elasticsearch]$ ./gradlew assemble --parallel
[jason@totoro elasticsearch-6.x]$ find . -name "build-tools*.pom"
./buildSrc/build/distributions/build-tools-6.4.0-SNAPSHOT.pom
[jason@totoro elasticsearch-6.x]$ cat ./buildSrc/build/distributions/build-tools-6.4.0-SNAPSHOT.pom
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.elasticsearch.gradle</groupId>
  <artifactId>build-tools</artifactId>
  <version>6.4.0-SNAPSHOT</version>
  <dependencies>
    <dependency>
      <groupId>com.carrotsearch.randomizedtesting</groupId>
      <artifactId>junit4-ant</artifactId>
      <version>2.5.2</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.carrotsearch.randomizedtesting</groupId>
      <artifactId>randomizedtesting-runner</artifactId>
      <version>2.5.2</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.netflix.nebula</groupId>
      <artifactId>gradle-extra-configurations-plugin</artifactId>
      <version>3.0.3</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.netflix.nebula</groupId>
      <artifactId>nebula-publishing-plugin</artifactId>
      <version>4.4.4</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.netflix.nebula</groupId>
      <artifactId>gradle-info-plugin</artifactId>
      <version>3.0.3</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.eclipse.jgit</groupId>
      <artifactId>org.eclipse.jgit</artifactId>
      <version>3.2.0.201312181205-r</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.perforce</groupId>
      <artifactId>p4java</artifactId>
      <version>2012.3.551082</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>de.thetaphi</groupId>
      <artifactId>forbiddenapis</artifactId>
      <version>2.5</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.rat</groupId>
      <artifactId>apache-rat</artifactId>
      <version>0.11</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.elasticsearch</groupId>
      <artifactId>jna</artifactId>
      <version>4.5.1</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.github.jengelman.gradle.plugins</groupId>
      <artifactId>shadow</artifactId>
      <version>2.0.4</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
  <inceptionYear>2009</inceptionYear>
  <licenses>
    <license>
      <name>The Apache Software License, Version 2.0</name>
      <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
      <distribution>repo</distribution>
    </license>
  </licenses>
  <developers>
    <developer>
      <name>Elastic</name>
      <url>http://www.elastic.co</url>
    </developer>
  </developers>
  <name>build-tools</name>
  <description>Elasticsearch subproject :build-tools</description>
  <url/>
  <scm>
    <url/>
  </scm>
</project>
[jason@totoro elasticsearch-6.x]$ 

[nik9000]

Merged and backported to 6.x and 6.4!