Make default timeout for codeception into env var

In some cases, we're seeing timeouts on test runs from the selenium web driver. This might be an inability to resolve the server, but could also be that things are just exceptionally slow sometimes.

Being able to configure the default codeception timeout globally could be very useful for debugging but also for making sure test runs are consistent in their outcome.

Acceptance criteria:

- [ ] Default codeception timeout value can be set via an environment variable at run time called `CODECEPT_TIMEOUT`
- [ ] Validate that the timeout is applied on long running tests
- [ ] Add documentation about the variable

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## For Altis Team Use

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