unrelated_type_equality_checks tests should include relational patterns

[srawlins]

Child issue of #58837

For example:

String asciiCharType(int char) {
  const space = 32;
  const zero = 48;
  const nine = 57;

  return switch (char) {
    == 'space' => 'space', // LINT
    // Etc...
  };
}