tools: avoid repeated subtree scans in must-call-assert

Match the promise call chain before checking for a descendant return
statement, preserving the existing lint checks.

Assisted-by: Codex
Signed-off-by: inoway46 <inoueyuya416@gmail.com>
PR-URL: #66408
Refs: #64972
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>

Author: inoway46

tools/eslint-rules/must-call-assert.js

@@ -135,10 +135,11 @@ module.exports = {
         });
       },
 
-      [`CallExpression[callee.property.name="then"][arguments.length=1]>CallExpression:matches(${[
+      // Check the call chain before searching descendants for a return.
+      [`:matches(CallExpression[callee.property.name="then"][arguments.length=1]>CallExpression:matches(${[
         '[callee.name="mustCall"]',
         '[callee.object.name="common"][callee.property.name="mustCall"]',
-      ].join(',')})[arguments.length=1]>:has(ReturnStatement)`]: (node) => {
+      ].join(',')})[arguments.length=1]>*):has(ReturnStatement)`]: (node) => {
         context.report({
           node,
           message: 'Cannot mix `common.mustCall` and return statement inside a `.then` chain',