[random test failure] JsonApiFunctionalTest::testRead

// Test that logged in user does not get logged out in maintenance mode
// when hitting jsonapi route.
$this->container->get('state')->set('system.maintenance_mode', FALSE);
$this->drupalLogin($this->userCanViewProfiles);
$this->container->get('state')->set('system.maintenance_mode', TRUE);
$this->drupalGet('/jsonapi/taxonomy_term/tags');
$this->assertSession()->statusCodeEquals(503);

Sounds like state cache race condition. Probably needs WaitTerminateTestTrait.

Repeat 1000 times:

Run 1 - 7/1000 fails
Run 2 - 14/1000 fails
Run 3 - 10/1000 fails

With WaitTerminateTestTrait:

Run 1 - 2/1000 fails
Run 2 (after moving setWaitForTerminate) - 0/1000 fails
Run 3 - 0/1000 fails

I forgot to actually commit the code for Run 1 with WaitTerminateTestTrait, which is why it had 2 fails. I've moved the setWaitForTerminate call where I intended it to be the first time and ran it again:

Run 4 - 0 fails

I've hidden the 2 test branches and opened a new branch (MR !11640) with only the fix. This is ready for review.

Thanks, committed to 11.x