Don't publish the plugin twice.

When updating the publishing plugin, I must have fixed this block,
'cuz I accidentally published the plugin a second time.  Don't do that
again.

Author: ncalexan

plugin/build.gradle

@@ -6,17 +6,6 @@ apply plugin: "java-gradle-plugin"
 apply plugin: "maven-publish"
 apply plugin: "kotlin"
 
-gradlePlugin {
-    plugins {
-        simplePlugin {
-            id = 'org.mozilla.rust-android-gradle'
-            implementationClass = 'com.nishtahir.RustAndroidPlugin'
-            displayName = 'Plugin for building Rust with Cargo in Android projects'
-            description = 'A plugin that helps build Rust JNI libraries with Cargo for use in Android projects.'
-        }
-    }
-}
-
 group 'org.mozilla.rust-android-gradle'
 version "$plugin_version"