Per comment in the upstream release notes, the `beta` track is no longer
maintained, and parity only has `stable` releases, so this deletes the beta
expression entirely.
https://github.com/paritytech/parity-ethereum/releases
This also updates to the new fetchCargoTarball implementation as part of #79975
Changes the default fetcher in the Rust Platform to be the newer
`fetchCargoTarball`, and changes every application using the current default to
instead opt out.
This commit does not change any hashes or cause any rebuilds. Once integrated,
we will start deleting the opt-outs and recomputing hashes.
See #79975 for details.
