dillon1000/react

Fix sizebot (#15771)

The previous naming scheme used the name of the resulting bundle file.
However, there are cases where multiple bundles have the same filename.
This meant whichever bundle finishes last overwrites the previous ones
with the same name.

The updated naming scheme is `bundle-sizes-<CI_NODE_INDEX>.json`.
Instead of generating a separate info file per bundle, it now creates
one per process.