Removing deprecated tasks

[missymessa]

Hi dotnet/spark,

The .NET Eng Services team is fully deprecating a couple of custom Azure DevOps tasks that haven't been used in many years. This PR is to clean up usage of those tasks.

Thanks!
Missy

See: dotnet/dnceng#507

We are excited to review your PR.

So we can do the best job, please check:

• There's a descriptive title that will make sense to other developers some time from now.
• There's associated issues. All PR's should have issue(s) associated - unless a trivial self-evident change such as fixing a typo. You can use the format Fixes #nnnn in your description to cause GitHub to automatically close the issue(s) when your PR is merged.
• Your change description explains what the change does, why you chose your approach, and anything else that reviewers should know.
• You have included any necessary tests in the same PR.

[wudanzy]

Hi @missymessa , is this PR still needed?

[grazy27]

Hi @missymessa , is this PR still needed?

Everything inside eng\common is defined in Arcade, and should be copied from there.
For other dotnet repos, there's a bot that automatically creates a PR and overwrites changes for Arcade each release.

Btw, it seems we don't use these yamls at all, since new pipelines are defined separately

[missymessa]

Up to you all if you think this is still necessary. At the time this PR was created, this repo had the tasks that we were removing, so we wanted to do our due diligence to make sure we weren't breaking folks. Feel free to close it!