Add useless prefix try_into_ for suggest_name

[A4-Tacks]

Example

enum Foo {
    Num(i32)
}

impl Foo {
    fn try_into_num(self) -> Result<i32, Self> {
        if let Self::Num(v) = self {
            Ok(v)
        } else {
            Err(self)
        }
    }
}
fn handle(foo: Foo) {
    foo.try_into_num().$0
}

Before this PR

fn handle(foo: Foo) {
    if let Ok(${1:try_into_num}) = foo.try_into_num() {
        $0
    }
}

After this PR

fn handle(foo: Foo) {
    if let Ok(${1:num}) = foo.try_into_num() {
        $0
    }
}