Windows SaaS Runner enable core.longpaths true

Background

Windows SaaS Runners encounter errors when fetching repo data due to large filenames not being supported. See below for excellent explanation from Stack Overflow: https://stackoverflow.com/a/22575737

We have documented methods for working around or resolving these errors, however customers using Windows SaaS Runners don't have the option of setting core.longpaths true. https://docs.gitlab.com/runner/install/windows.html#i-get-a-pathtoolongexception-during-my-builds-on-windows

In some cases, customers have the option to host their own Windows Runner, or use a competitor's CI/CD service. In one case, the customer has opted to use a competitor's CI/CD service instead due to the lack of support for longpaths.

Proposal

Ensure that Windows SaaS Runners support longpaths by default.