Adopt LazyLock for global singletons in Rust 1.80+

[lalitb]

          Using a [`LazyLock`](https://doc.rust-lang.org/std/sync/struct.LazyLock.html) here should be even simpler but it requires `1.80+` version of Rust. We could probably add a TODO or create an issue to revisit this when we move to that version of Rust.

Originally posted by @utpilla in #2326 (comment)