refactor(lexer): #[inline(always)] on Walks::run_rules (#28648)

Part of effort to move to runtime CPU feature detection. Follow-up after auditing codegen after work so far in this stack.

`Walks::run_rules` is Level 3 code, but `gt_run_split` calls it from Level 2. Outside tests, it only returns `true`, and that must fold into `gt_run_split`. So it gets `#[inline(always)]` instead of `cpu_versions!` or `#[inline(never)]`. Its test version too, so both versions are the same shape.

Codegen: no change in any build. It was already inlined everywhere.

crates/oxc_lexer/src/pipeline/disambiguate/context/mod.rs

@@ -83,11 +83,13 @@ impl Walks {
     }
 
     #[cfg(test)]
+    #[inline(always)]
     pub(super) fn run_rules(&self) -> bool {
         !self.full_walk_only && !self.no_run_rules
     }
 
     #[cfg(not(test))]
+    #[inline(always)]
     pub(super) fn run_rules(&self) -> bool {
         true
     }