Update product DRIs and rituals (#14690)

- "Head of Product" => "Head of Product Design"
- #help-product => #help-product-design
- "Sprint kickoff review" is now one ritual that includes both MDM and
Endpoint ops teams
- "Pre-sprint prioritization" ritual is now one ritual that includes
both MDM and Endpoint ops teams
- Remove "Sprint release notes kickoff" ritual. Plan is to inform
#g-demand of new features asynchronously. Any discussion that needs to
happen live will happen at product office hours
- Remove "Report number of estimated stories (Endpoint ops))" and
"Report number of estimated stories (MDM)" rituals. One person (Head of
Product Design) is both reporting and tracking product KPIs
- Remove "Bug de-prioritization" ritual. Trying this instead: ~~CEO,~~
Head of Product Design, and Head of Product Development align on next
steps for which bugs to schedule into the next sprint and which can be
de-prioritized during the "Churned bug review" ritual. Less meetings.

---------

Co-authored-by: Mike McNeil <mikermcneil@users.noreply.github.com>

.github/ISSUE_TEMPLATE/smoke-tests.md

@@ -78,7 +78,7 @@ Using the migration scripts located in fleet/test/upgrade/
 <tr><td>Release blockers</td><td>Verify there are no outstanding release blocking tickets.</td><td>
   
 1. Check [this](https://github.com/fleetdm/fleet/labels/~release%20blocker) filter to view all open `~release blocker` tickets.
-2. If any are found raise an alarm in the `#help-engineering` and `#help-product` channels.
+2. If any are found raise an alarm in the `#help-engineering` and `#help-product-design` channels.
 </td><td>pass/fail</td></tr>
 </table>