Remove preview gating for pycodestyle rules (#9685)

## Summary

Un-gates the behavior to allow `sys.path` modifications between imports,
which removed a bunch of false positives in the ecosystem CI at the
time.

crates/ruff_linter/src/checkers/ast/mod.rs

@@ -342,8 +342,7 @@ where
                     || helpers::is_assignment_to_a_dunder(stmt)
                     || helpers::in_nested_block(self.semantic.current_statements())
                     || imports::is_matplotlib_activation(stmt, self.semantic())
-                    || self.settings.preview.is_enabled()
-                        && imports::is_sys_path_modification(stmt, self.semantic()))
+                    || imports::is_sys_path_modification(stmt, self.semantic()))
                 {
                     self.semantic.flags |= SemanticModelFlags::IMPORT_BOUNDARY;
                 }

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

@@ -68,7 +68,6 @@ mod tests {
     }
 
     #[test_case(Rule::IsLiteral, Path::new("constant_literals.py"))]
-    #[test_case(Rule::ModuleImportNotAtTopOfFile, Path::new("E402_0.py"))]
     #[test_case(Rule::TypeComparison, Path::new("E721.py"))]
     fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!(

crates/ruff_linter/src/rules/pycodestyle/snapshots/ruff_linter__rules__pycodestyle__tests__E402_E402_0.py.snap

@@ -1,36 +1,6 @@
 ---
 source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
 ---
-E402_0.py:25:1: E402 Module level import not at top of file
-   |
-23 | sys.path.insert(0, "some/path")
-24 | 
-25 | import f
-   | ^^^^^^^^ E402
-26 | 
-27 | import matplotlib
-   |
-
-E402_0.py:27:1: E402 Module level import not at top of file
-   |
-25 | import f
-26 | 
-27 | import matplotlib
-   | ^^^^^^^^^^^^^^^^^ E402
-28 | 
-29 | matplotlib.use("Agg")
-   |
-
-E402_0.py:31:1: E402 Module level import not at top of file
-   |
-29 | matplotlib.use("Agg")
-30 | 
-31 | import g
-   | ^^^^^^^^ E402
-32 | 
-33 | __some__magic = 1
-   |
-
 E402_0.py:35:1: E402 Module level import not at top of file
    |
 33 | __some__magic = 1