Protect building the repository without a source control provider available

[ViktorHofer]

We had numerous incidents in the past where the repository wasn't buildable without the ".git" folder being available. This should be protected by nuking the .git folder away after fetching the repo (checkout) and passing in /p:DisableSourceLink (which is necessary as source link by default is only disabled locally, when not in CI).

More context in #47130.

Tagging subscribers to this area: @ViktorHofer
See info in area-owners.md if you want to be subscribed.

Issue Details

---

We had numerous incidents in the past where the repository wasn't buildable without the ".git" folder being available. This should be protected by nuking the .git folder away after fetching the repo (checkout) and passing in /p:DisableSourceLink (which is necessary as source link by default is only disabled locally, when not in CI).

More context in #47130.

Author:	ViktorHofer
Assignees:	-
Labels:	area-Infrastructure
Milestone:	6.0.0

[dotnet-policy-service]

Due to lack of recent activity, this issue has been marked as a candidate for backlog cleanup. It will be closed if no further activity occurs within 14 more days. Any new comment (by anyone, not necessarily the author) will undo this process.

This process is part of our issue cleanup automation.

[dotnet-policy-service]

This issue will now be closed since it had been marked no-recent-activity but received no further activity in the past 14 days. It is still possible to reopen or comment on the issue, but please note that the issue will be locked if it remains inactive for another 30 days.