Set certificate in some Kestrel tests to avoid global machine state

[BrennanConroy]

There were some changes to dev certs which is causing hangs in Kestrel tests in #21017. This is because the tests were relying on the dev cert being allowed globally on the test machine, when they should be providing a cert so they don't rely on global state.

Also added a little bit extra test coverage to the existing tests.

[Pilchie]

👀

[dougbu]

👁️ have a question: What's the advantage of an 👀 question over an 👀 reaction to the PR description and clicking the Subscribe button❔ (I understand just clicking Subscribe is invisible and we often want people to know we're looking.)

[BrennanConroy]

Putting 👀 (or any comment) will add you to the mentions in the email metadata, so you can easily filter issues that you're actually interested in. Kevin told me once that he was subscribed to everything and I am too, I know that I have filters based on the email metadata so adding those kinds of comments are super useful for getting updates.

[dougbu]

Should have said

Unfortunately https://netcorenativeassets.blob.core.windows.net seems to have been flaky during the build. See also #20577 though a retry will be needed here.

[Pilchie]

Yep, @BrennanConroy nailed why I use 👀. I get email for anything I'm "participating", but see the rest of my notifications in the GitHub notifications UI.

[javiercn]

We probably want to port this back to 3.1 too

[dougbu]

We probably want to port this back to 3.1 too

No disagreement here. It's a test-only change and can therefore be merged whenever the branch is open. @BrennanConroy❔

Same thing for d640937 aka #21493 @javiercn❔

[BrennanConroy]

Sure, I'll make a PR for this one

[javiercn]

Same thing for d640937 aka #21493 @javiercn❔

I already have a PR out for it #21496