Fix several test issues exposed by the ResolvedAddresses refactor:
- TestTagUserMutualExclusivity: remove incorrect ACL rule that was
testing the wrong invariant. The test now correctly validates that
without an explicit cross-identity grant, user-owned nodes cannot
reach tagged nodes. Add TestUserToTagCrossIdentityGrant to verify
that explicit user@ -> tag:X ACL rules produce valid filter rules.
- TestResolvePolicy/wildcard-alias: update expected prefixes to match
the CGNAT range minus ChromeOS VM range (multiple prefixes instead
of the encompassing 100.64.0.0/10).
- TestApproveRoutesWithPolicy: fix user Name fields from "testuser@"
to "testuser" to match how resolveUser trims the @ suffix before
comparing against stored names.
Updates #2180