Update to LMS/Studio shared-session deprecation: Will be included in Maple

I previously announced DEPR-166, the splitting of the LMS and Studio session cookies: Deprecation/Removal: LMS/Studio shared session and cookie (DEPR-166)

We’ve passed the acceptance date, but I’ve since moved up the “removal” date to October 1, before the Maple branches are cut. If there turn out to be any blockers for Maple (such as in the new setup instructions or scripts) we can always roll it back just on the Maple branches.

(I had previously chose the post-Maple date to provide more timing flexibility to deployers, but this really should be a pretty straightforward transition – and also should be possible to override with just settings, if needed.)