Make jest maxWorkers more robust and adaptable

[ilia-kebets-sonarsource]

We have currently 2 values that must work in concert for the CI:

• task.cpu in cirrus.yml
• maxWorkers parameter in jest command in package.json

PR: #4583

To make this more robust, we will introduce a test that checks that these 2 values respect the following formula:

maxWorkers = CPU - 2

We would like the value of maxWorkers to be more easily adaptable on dev machines, since the hardware is varied and different from our CI.
For this, we would need to have a different test command executed whether or not IS_CI is true.
We would probably keep a % value for maxWorkers for the dev environment.

[Wohops]

Migrated to Jira. New ticket number: JS-27