fix: Set global timeout conditionally

[alexplischke]

Set the global timeout conditionally, that is, the user didn't set one in their native playwright config file. This allows the user to retain their existing timeout configuration and still be able to override it if necessary via saucectl.

This fix addresses the following issues:

• The default timeout for the entire execution was incorrectly set as the test level timeout
• The default acted as a constant override, rather than default, causing customer provided values inside the native playwright config to be overridden at all times
• The user had to set both the globalTimeout and the regular timeout, so that timeout wasn't overridden by the default

Here's an example job where I set the test timeout via the playwright configuration file (forcing it to fail): https://app.saucelabs.com/tests/2a7e89f34ea94ff599d84d8ad3d3eb61