Port "ignore nonexistent queue" functionality to release/5.0

[MattGal]

To double check:

• The right tests are in and and the right validation has happened. Guidance: https://github.com/dotnet/core-eng/tree/master/Documentation/Validation (tested in PR validation)

Description

Context: https://github.com/dotnet/core-eng/issues/14572
Port of #8069 (bbb4187). Allows users who want to to ignore non-existent Helix queues, so we don't have to keep every queue that we've ever had in existence in our yaml files forever.

Customer Impact

This change allows customers to decide whether their build should break (and thus require attention) when sending to and end-of-life-d queue, or just print a warning.

Without this change, any old queue that has been removed (e.g. OSX.1012.Amd64) will cause failure once the changes to do this are merged.

Regression

No

Risk

Low; only two queues we'd remove (osx.1012.amd64, redhat.6.amd64) have been used in the past 30 days, from 3.1 release branches, and these can be left alone until addressed.

Workarounds

User will have to work around this by removing dead queues manually without this setting available in the Arcade SDK.