[stable31] fix: Only attempt $result array access if array not empty.

[joshtrichards]

• Resolves: [Bug]: "Undefined array key 0" when 'pwdpolicysubentry', 'pwdgraceusetime', 'pwdreset', 'pwdchangedtime' not exist #53713

Summary

Manual backport of #53714 (for some reason I can't trigger the backport on that PR at the moment).

TODO

• ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)