release: don't close issue before post-release steps

Created by: davejrt

There's some confusion around the order of steps in the release process. The issue should be closed after all steps, including setting up the next release are completed. The command is renamed to announce to more accurately describe what it's doing.

Thought about putting in a yarn close command here...but seems redundant given the release captain is reading the instructions, from an issue they can close manually.

fixes point 2 in: https://github.com/sourcegraph/sourcegraph/issues/31772

follow up handbook update: https://github.com/sourcegraph/sourcegraph/pull/38950

Test plan

n/a