Allow submitting code for review without waiting for Jenkins to run the entire test suite.

Let's explicitly allow submitting a branch immediately after running the
relevant test suite scenarios locally. This should make it possible for
a developer to start working on a ticket and submit the resulting branch for QA
in one single work session: while the branch builds on Jenkins, one can run the
relevant test suite scenarios locally. I hope this can lower the amount of WIP
developers carry and the number of context switches they have to do
(refs: #15864).

Worst case, we'll notice any test suite regression after the merge;
we can then revert the merge and nicely ask the branch submitter
to fix the regression before we merge it again.

wiki/src/contribute/merge_policy/submit.mdwn

@@ -19,14 +19,15 @@ When you think it is good enough and have tested it, you have to:
    or to a merge request on [Salsa](https://salsa.debian.org/tails-team/tails).
 4. Set the ticket's *Target version* field to the release you would
    like your changes to be in.
-5. If you have access to our Jenkins instance (if you don't know what
-   this means, you do not) please make sure that your branch has not
-   broken any tests! Or, if you only want a first review of your code,
-   without bothering with the build & test status on Jenkins, that's fine:
-   make it clear to the reviewer what you expect and
-   that your branch is not ready to merge.
-6. Set the ticket's *QA Check* field to *Ready for QA*.
-7. Assign the ticket to nobody (aka. unassign it from yourself) by
+5. Make it clear what you're requesting: merging? some advice? an initial
+   code review of work that's not finished yet?
+6. If you have access to our Jenkins instance and you are requesting a merge:
+   - Ensure your branch builds on Jenkins.
+   - Either report about the test suite scenarios you've seen pass
+     successfully locally, or check that the test suite passes
+     on Jenkins.
+7. Set the ticket's *QA Check* field to *Ready for QA*.
+8. Assign the ticket to nobody (aka. unassign it from yourself) by
    default. Unless it's clear to you that nobody on the
    [[Foundations Team|working_together/roles/foundations_team]] will be
    able or willing to do this specific review; in that case, _you_ shall try