Simplify find_attr!() for the case when a hir id is given

[JayanAXHF]

Simplify find_attr!() for the case when a hir id is given. This is a part of the attribute parser rework initiative under #131229.

cc: @JonathanBrouwer

[mehdiakiki]

I would like to give it a try! I will message you tomorrow in Zulip! @rustbot claim

[JayanAXHF]

Hey @mehdiakiki, thanks for showing interest. Check out the zulip thread at https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/attribute.20parsing.20rework/with/567166329 for a discussion on its implementation. Happy hacking :)