Remove Greaselion after Rewards stop using it

[atuchin-m]

Description

After brave/brave-core#25394 is merged and the new feature is considered as launched we don't need Greaselion code anymore.
The overlay idea of Greaselion is good, but the implementation is limited and has the number of issues:

1. slows down the startup
2. make a scoped_temp_dir folder in user-data-dir
3. user a number of extension instead of a one
4. doesn't support android

If we really need this feature is should be reimplemented.

[atuchin-m]

As the first step Greaselion should be disabled for the most of Brave users: #40872