SAST_EXCLUDED_PATHS shouldn't have spaces

[jameshartig]

docs/troubleshooting/gitlab-sast.md has SAST_EXCLUDED_PATHS: "*.py, tests" but when GitLab converts that to --exclude rules it ends up as --exclude *.py --exclude tests where there's 2 spaces before tests. This was causing semgrep to not ignore paths containing "tests" because, I imagine, it's looking for " tests". I'm not sure if there should be follow-up issues for GitLab or semgrep but for now, the docs shouldn't suggest a broken value.

[s-santillan]

@jameshartig Hi James! We will look into this. Thanks for opening an issue.

[s-santillan]

Filed ticket CSE-115 internally to track.