frame-benchmarking: Macros should not force a particular env (#13161)

The macros in frame-benchmarking relied on having all the macros imported, which isn't a behavior
for a proper macro :D This pr fixes this by making all internal macro usages absolute.

substrate/bin/node/runtime/src/lib.rs

@@ -1823,13 +1823,9 @@ mod mmr {
 	pub type Hashing = <Runtime as pallet_mmr::Config>::Hashing;
 }
 
-#[cfg(feature = "runtime-benchmarks")]
-#[macro_use]
-extern crate frame_benchmarking;
-
 #[cfg(feature = "runtime-benchmarks")]
 mod benches {
-	define_benchmarks!(
+	frame_benchmarking::define_benchmarks!(
 		[frame_benchmarking, BaselineBench::<Runtime>]
 		[pallet_alliance, Alliance]
 		[pallet_assets, Assets]