Pass distribution type through to docs tests (elastic#37885)

This commit fixes the distribution flavor passed to the docs tests to be
the same as the distribution. These two values are now in sync (either
oss or default) for the docs tests.

Author: rjernst

buildSrc/src/main/groovy/org/elasticsearch/gradle/doc/DocsTestPlugin.groovy

@@ -45,8 +45,7 @@ public class DocsTestPlugin extends RestTestPlugin {
             '\\{version\\}': Version.fromString(VersionProperties.elasticsearch).toString(),
             '\\{version_qualified\\}': VersionProperties.elasticsearch,
             '\\{lucene_version\\}' : VersionProperties.lucene.replaceAll('-snapshot-\\w+$', ''),
-            '\\{build_flavor\\}' :
-                project.integTestCluster.distribution.startsWith('oss-') ? 'oss' : 'default',
+            '\\{build_flavor\\}' : project.integTestCluster.distribution,
         ]
         Task listSnippets = project.tasks.create('listSnippets', SnippetsTask)
         listSnippets.group 'Docs'