Bug 1426244 - Follow-up to use new variant; r=me

Use the new variant 'officialWithGeckoBinariesNoMinApiRelease', which is
used by other m-c build jobs, for building javadoc.

testing/mozharness/configs/builds/releng_sub_android_configs/64_geckoview_docs.py

@@ -13,6 +13,7 @@ config = {
          '--upload', 'mozilla/geckoview',
          '--upload-branch', 'gh-pages/javadoc/{project}',
          '--upload-message', 'Update {project} javadoc to rev {revision}',
+         '--variant', 'officialWithGeckoBinariesNoMinApiRelease',
         ],
     ],
     'artifact_flag_build_variant_in_try': None, # There's no artifact equivalent.