Wait for preparing tasks to submit before auto restart

[MetRonnie]

Fix bug where any preparing local jobs would get orphaned during the shutdown before an auto restart.

You could reproduce this bug by changing

diff --git a/tests/functional/restart/42-auto-restart-ping-pong.t b/tests/functional/restart/42-auto-restart-ping-pong.t
index 5f897b33e..ecf58e99f 100644
--- a/tests/functional/restart/42-auto-restart-ping-pong.t
+++ b/tests/functional/restart/42-auto-restart-ping-pong.t
@@ -74,5 +74,5 @@ log_scan2() {
 }
 
-EARS=5  # number of times to bounce the workflow between hosts
+EARS=40  # number of times to bounce the workflow between hosts
 NO_TESTS="$(( EARS * 5 + 1 ))"
 set_test_number "${NO_TESTS}"

and running the test, eventually it would orphan a preparing job and cause the test to fail.

Check List

• I have read CONTRIBUTING.md and added my name as a Code Contributor.
• Contains logically grouped changes (else tidy your branch by rebase).
• Does not contain off-topic changes (use other PRs for other changes).
• No dependency changes
• Tests are included
• CHANGES.md entry included if this is a change that can affect users
• No docs needed
• If this is a bug fix, PRs raised to both master and the relevant maintenance branch.

[oliver-sanders]

LGTM.

• Tested by breaking the job-submission pipeline after the "prep" stage to ensure auto-restart is delayed by preparing jobs.
• Ran the functional/flakyfunctional restart tests locally (not run by CI).

[oliver-sanders]

(could do with a changelog entry for this one)

[wxtim]

Suggested change

	log = LOG.debug
	if self.options.reftest or self.options.genref:
	log = LOG.info
	log = LOG.info if (self.options.reftest or self.options.genref) else LOG.debug

[MetRonnie]

Doesn't fit on 1 line which is why I left it the way it is