Use rustc_lint's `is_ty_must_use`

[samueltardieu]

Description

Once rust-lang/rust#148214 is merged, it would be if Clippy could use rustc_lint's is_ty_must_use instead of having its own (currently outdated) view of the situation.

See this Zulip thread for more context.

Version

Additional Labels

No response

[WaffleLapkin]

rust-lang/rust#153018 has merged so this is not blocked anymore
@rustbot label -S-blocked