Space in extension path: Make testing part of insiders.yml/release.yml

[rchiodo]

After all of these issues are fixed:
#14163
#14164
#14165
#14166
#14167

Submit this pr here (after modifying it to not run on that specific branch):
#14113

[kimadeline]

@rchiodo Do we need a separate PR for release.yml, or can we consider this done?

[rchiodo]

I guess that's open for discussion? I think insiders testing of spaces is probably good enough. It should catch any errors before they get into the release branch. So I'd say this is done. But if you guys want to double check the release branch too, feel free to copy the changes to the release.yml.

[kimadeline]

Eventually we should also make sure the release branch also runs tests with spaces in the extension path, but we're not going to address it right now 👉 Leaving the issue open but removing the P1 label.

Update: we're going to deal with it now, and make similar changes to the release workflow.