Remove interop-2021 label from tentative tests

[foolip]

Matches Ecosystem-Infra/wpt-results-analysis#67.

[nt1m]

@foolip Is this something we still want to do?

[foolip]

@nt1m I think we should review these tests and decide individually. IIRC I brought this up in a meeting, but we didn't give an action item to anyone so it's just sitting here.

As step 1 I'll rebase this to resolve conflicts.

[foolip]

Here are the results of these tests:
https://wpt.fyi/results/css?label=master&label=experimental&product=chrome&product=firefox&product=safari&aligned&view=interop&q=tentative%20and%20%28label%3Ainterop-2021-aspect-ratio%20or%20label%3Ainterop-2021-flexbox%20or%20label%3Ainterop-2021-grid%20or%20label%3Ainterop-2021-position-sticky%20or%20label%3Ainterop-2021-transforms%29

[foolip]

So they're actually passing everywhere, making it low priority to figure out if they should be tentative still or not.

If someone would like to remove them an issue on https://github.com/web-platform-tests/interop-2022/issues would be the way to go. These test lists were reviewed when we agreed on Interop 2022, so we shouldn't drop them without discussion.

I'll mark this PR as draft since I'm not planning to do anything with it myself right now.

[foolip]

web-platform-tests/results-analysis#66 is the corresponding draft PR for the scoring script. (The Compat 2021 scoring script doesn't use the labels like Interop 2022 does.)