Stable: Backports (#8986)

* snap: downgrade rust to revision 1.26.2, ref snapcraft/+bug/1778530 (#8984)

* snap: downgrade rust to revision 1.26.2, ref snapcraft/+bug/1778530

* snap: use plugin rust

* Fix deadlock in blockchain. (#8977)

* Remove js-glue from workspace

This fixes test error on Rust 1.27 but also prevents js-glue from building itself. Builtin dapp users can still use
js-glue from crates.io.