Build: Remove maven central snapshots from repositories (#20567)

We were using maven snapshots during heavy development, but this should
not be something generally available (we should never release depending
on a snapshot version in maven). This change removes the snapshot repo.
If we ever need it temporarily for some reason, we can add it if/when
it is necessary.

relates #20559

buildSrc/build.gradle

@@ -109,10 +109,6 @@ if (project == rootProject) {
 
   repositories {
     mavenCentral()
-    maven {
-      name 'sonatype-snapshots'
-      url "https://oss.sonatype.org/content/repositories/snapshots/"
-    }
   }
   test.exclude 'org/elasticsearch/test/NamingConventionsCheckBadClasses*'
 }

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -284,10 +284,6 @@ class BuildPlugin implements Plugin<Project> {
             repos.mavenLocal()
         }
         repos.mavenCentral()
-        repos.maven {
-            name 'sonatype-snapshots'
-            url 'http://oss.sonatype.org/content/repositories/snapshots/'
-        }
         String luceneVersion = VersionProperties.lucene
         if (luceneVersion.contains('-snapshot')) {
             // extract the revision number from the version with a regex matcher