renderer: Show install steps on manual testcases as well

The pre-condition steps generated by the install/git-repos directives where only rendered for automated testcases. Arguably, manual testers are more interested in those being rendered than LAVA, which usually considers the YAML enough as-is.

This currently affected the WebKit manual testcases such as webkit2gtk-ac-3d-rendering.yaml where no installation pre-condition was rendered, omitting fundamental steps needed by manual testers.