Remove accidental files included inside the template.

Summary:
Those files should not stay in the root `/app` folder but inside the `/app/gradle/wrapper` folder.
I've noticed this in the Upgrade Helper UI hence I'm removing them.

Changelog:
[Internal] [Changed] - Remove accidental files included inside the template

Reviewed By: mdvacca

Differential Revision: D54122995

fbshipit-source-id: 8873a91ffbea20f609c7aabd428a815c77a38db5

Author: cortinico