fix : remove _{ } syntax from benchmark macro (#7822)

* commented use of common

* hack to pass tests

* another hack

* remove all commented code

* fix the easy tests

* temp hack

* follow through comma hack until better solution

* patch macro

* missed one

* update benchmarks

* update docs

* fix docs

* removed too much

* fix changes

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/session/benchmarking/src/lib.rs

@@ -51,8 +51,6 @@ impl<T: Config> OnInitialize<T::BlockNumber> for Module<T> {
 }
 
 benchmarks! {
-	_ {	}
-
 	set_keys {
 		let n = MAX_NOMINATIONS as u32;
 		let (v_stash, _) = create_validator_with_nominators::<T>(