suite-restart vs suite-run --restart and Cylc version

[hjoliver]

rose suite-restart invokes cylc restart using CYLC_VERSION from the environment

rose suite-run --restart preserves the suite's original CYLC_VERSION regardless of user environment

As a consequence, users can upgrade CYLC_VERSION in the environment and restart a suite at the new versions with rose suite-restart, then weeks later (say) stop and restart again with rose suite-run --restart (to install some changes) ... and Cylc will start up again with the original (not the previous!) version.

Probably not worth fixing this now, but we should fix it (perhaps by ditching automatic version preservation entirely) during rose suite-run migration to Cylc.