Cannot suppress errors in $refs using "where" clauses

[mikeharder]

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 $refs 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.