minifier: remove no-op function call

[sapphi-red]

function foo() {}
foo()

const bar = () =>{}
bar()

can be replaced with

function foo() {}
const bar = () =>{}

playground

---

With #11470 + #10033 + this,

let foo = {}
function _setFoo(bar) {
  foo = bar
}
const baz = ""
_setFoo(baz)

export { baz }

can be simplified to

const baz = ""
export { baz }

(this case is generated by astro)

[sapphi-red]

implemented by #12373