This change corrects all crate patches, changing them to point to
`brave/`. This eliminates the need of patching `gnrt vendor` to address
this patch mismatch.
Patches should be created now with:
```sh
git format-patch \
--start-number=101 \
--src-prefix=a/brave/ \
--dst-prefix=b/brave/ \
--output-directory \
third_party/rust/chromium_crates_io/patches/some-crate/ \
HEAD^
```
Resolves https://github.com/brave/brave-browser/issues/46201