fix(queue_job): out-of-the-box support in test environments

[yajo]

When you use queue_job, it is common to add some configuration to it.

The canonical way to do that with doodba would be to put a file in some path such as odoo/custom/conf.d/queue_job.conf and contents like these:

[options]
(...)
workers = 6
server_wide_modules = base,web,queue_job

(...)
[queue_job]
channels = root:3

However, in that case, the file would be used too by a test environment.

Test environments have 2 workers hardcoded, to save computational power for the production instance: https://github.com/Tecnativa/doodba-copier-template/blob/e2f4efdab336d5cd32c327a007983011e1e4edbb/test.yaml.jinja#L50

However, if you configure 2 workers with channels = root:3, you're doomed. Any delayed action in a test environment will block the server. At least, if the amount of delayed actions in batch is more than the current workers.

I'm adding docs to queue_job in https://github.com/OCA/queue/pull/650 to make this behavior clear. Also, here I'm adding an environment variable that will be harmless in test environments without queue_job, but will provide a sane default for those that use it.

@moduon MT-6106

[pedrobaeza]

And what happen if you define other subchannels with more capacity? Are all of them limited by the general one?

The CI is also broken, don't know why.

[yajo]

And what happen if you define other subchannels with more capacity? Are all of them limited by the general one?

The docs say that the number of workers should be greater than the number of channels. How you segregate those channels won't change that sentence AFAIK.

Since environment variables get higher priority than file configs, in the test environment there'll be no other channels with this fix.

I ammended to see if the tests were failing just temporarily.