Certain files (such as android/**/GeneratedPluginRegistrant.java) should never exist #143782
Description
See flutter/engine#50795.
A .gitignore file is useful to keeping the source tree and CI from being corrupted, but actually papers over the fact that it's easy to corrupt your local source directory. One off-the-wall suggestion with @zanderso and @dnfield was some sort tool/check that verifies that the source tree never contains certain files.
As a strawman, a .gitnogoaway:
**/android/**/GeneratedPluginRegistrant.java... which is failed if it exists on CI or locally.
There is an existing file that matches this pattern in our source tree, so we'll need to rename that file.