[For dev: update with main] Issue #535: Change multidev deploy to manual only: tag based

[YesCT]

Relates to:

• #535

Description:

• Run the Multidev Deploy when the label pantheon-multidev is added

Next steps

• Address feedback

References

From justafish

Here's the relevant bit of code that will need modifying https://github.com/Lullabot/drainpipe/blob/main/src/ScaffoldInstallerPlugin.php#L285

https://github.com/Lullabot/drainpipe/pull/546#issuecomment-2082805879