chore: remove test code

This reverts commit 90a1d37.

Author: ascorbic

src/index.js

@@ -65,8 +65,7 @@ module.exports = {
     })
   },
 
-  async onPostBuild({ netlifyConfig, utils: { cache, run }, constants: { FUNCTIONS_DIST } }) {
-    await run('cp', ['-v', join(FUNCTIONS_DIST, '_ipx.zip'), `${netlifyConfig.build.publish}/ipx.zip`])
+  async onPostBuild({ netlifyConfig, utils: { cache } }) {
     return saveCache({ cache, publish: netlifyConfig.build.publish })
   },
   onEnd() {