[compiler] Remove @babel/plugin-proposal-private-methods (#34715)

redo of #34458 but fixing up prettier

Co-authored-by: Arnaud Barré <arnaud.barre@carbometrix.com>

DiffTrain build for [85c427d822baad6e654256b707b7d8755da7db26](https://github.com/facebook/react/commit/85c427d822baad6e654256b707b7d8755da7db26)