Enable or_fun_call lint to avoid unnecessary allocations (#7754)

### What

From the [lint
description](https://rust-lang.github.io/rust-clippy/master/index.html?search=or_fu#or_fun_call):

> The function will always be called. This is only bad if it allocates
or does some non-trivial amount of work.

But also:

> If the function has side-effects, not calling it will change the
semantic of the program, but you shouldn’t rely on that.
> 
> The lint also cannot figure out whether the function you call is
actually expensive to call or not.

Still worth it to keep our happy paths clean, imo.

Cargo.toml

@@ -278,6 +278,7 @@ non_zero_suggestions = "warn"
 nonstandard_macro_braces = "warn"
 option_as_ref_cloned = "warn"
 option_option = "warn"
+or_fun_call = "warn"
 path_buf_push_overwrite = "warn"
 pathbuf_init_then_push = "warn"
 precedence_bits = "warn"