Cannot suppress errors in $refs using "where" clauses

Is this PR, there are only 3 instances of vmTags.additionalProperties in the source code, but about 9 AvoidAdditionalProperties errors are reported, since the instances are consumed other places via $ref.

https://github.com/Azure/azure-rest-api-specs/pull/29101/checks?check_run_id=25631949240


Neither the spec author, nor I, was able to suppress the errors raised via properties inside `$ref`s using `where` clauses. So the spec author had to use a global suppress.

If #697 is fixed, this issue might be moot, since the errors will never be raised in the first place. But it would still be good to know **why** these can't be suppressed.