Rename --pruning and --keep-blocks to be more similar to one another (#11934)

* rename prunning and keep-blocks flags

* Add aliases in keep-blocks and pruning for backward compatibility

* Rename in code variables from  and  to  and

substrate/client/service/src/builder.rs

@@ -207,7 +207,7 @@ where
 			state_cache_child_ratio: config.state_cache_child_ratio.map(|v| (v, 100)),
 			state_pruning: config.state_pruning.clone(),
 			source: config.database.clone(),
-			keep_blocks: config.keep_blocks,
+			blocks_pruning: config.blocks_pruning,
 		};
 
 		let backend = new_db_backend(db_config)?;