Make range suppression test snapshot actually useful (#23251)

When range suppressions were stabilized in 0.15.0, this snapshot became
empty/useless because there was no longer a difference between the
normal and preview behaviors on the fixture file.

Author: amyreese

crates/ruff_linter/resources/test/fixtures/ruff/suppressions.py

@@ -41,8 +41,8 @@ def f():
 
 
 def f():
-    # Neither of these are ignored and warnings are
-    # logged to user
+    # Neither of these are ignored and warnings are logged to user.
+    # An usued suppression diagnostic should also be logged.
     # ruff: disable[E501]
     I = 1
     # ruff: enable[E501]

crates/ruff_linter/src/rules/ruff/mod.rs

@@ -331,7 +331,7 @@ mod tests {
 
     #[test]
     fn range_suppressions() -> Result<()> {
-        assert_diagnostics_diff!(
+        let diagnostics = test_path(
             Path::new("ruff/suppressions.py"),
             &settings::LinterSettings::for_rules(vec![
                 Rule::UnusedVariable,
@@ -342,17 +342,8 @@ mod tests {
                 Rule::UnmatchedSuppressionComment,
             ])
             .with_external_rules(&["TK421"]),
-            &settings::LinterSettings::for_rules(vec![
-                Rule::UnusedVariable,
-                Rule::AmbiguousVariableName,
-                Rule::UnusedNOQA,
-                Rule::InvalidRuleCode,
-                Rule::InvalidSuppressionComment,
-                Rule::UnmatchedSuppressionComment,
-            ])
-            .with_external_rules(&["TK421"])
-            .with_preview_mode(),
-        );
+        )?;
+        assert_diagnostics!(diagnostics);
         Ok(())
     }