Update `It_warns_on_nonportable_rids` test once corresponding installer changes flow to sdk repo

[elinor-fung]

_KnownRuntimeIdentiferPlatforms is defined by BundledVersions.props from the installer repo. The It_warns_on_nonportable_rids test currently adds a subset of the expected list. It should be removed once the changes from installer (dotnet/installer#16578) flow to sdk.

It's probably a good idea to go back and delete this once the installer changes have been merged and flowed into stage 0.

Originally posted by @dsplaisted in #32970 (comment)