PR CL items missing for upgrade instructions

[dsotirho-ucsc]

We have upgrade-related PR CL items for the author, but none for the operator or other developers.

Add CL items for

1. applying upgrade instructions to shared deployments affected by the PR
2. notifying developers to apply upgrade instructions to their personal deployments

Note that item 2 would be absent from PRs that target the stable branches. The escape hatches are either A) the PR is not labelled upgrade or B), if it is, the instructions don't apply to the deployment in question.