Relaxed clippy fixes/nits (#2661)

This PR contains just a few clippy fixes and nits, which are, however,
relaxed by workspace clippy settings here:
https://github.com/paritytech/polkadot-sdk/blob/master/Cargo.toml#L483-L506

---------

Co-authored-by: Dmitry Sinyavin <dmitry.sinyavin@parity.io>
Co-authored-by: ordian <write@reusable.software>
Co-authored-by: command-bot <>
Co-authored-by: Bastian Köcher <git@kchr.de>

cumulus/parachains/runtimes/contracts/contracts-rococo/src/contracts.rs

@@ -26,7 +26,7 @@ use pallet_contracts::{
 };
 use sp_runtime::Perbill;
 
-pub use parachains_common::{rococo::currency::deposit, AVERAGE_ON_INITIALIZE_RATIO};
+pub use parachains_common::rococo::currency::deposit;
 
 // Prints debug output of the `contracts` pallet to stdout if the node is
 // started with `-lruntime::contracts=debug`.

cumulus/parachains/runtimes/contracts/contracts-rococo/src/weights/mod.rs

@@ -24,5 +24,4 @@ pub mod rocksdb_weights;
 
 pub use block_weights::constants::BlockExecutionWeight;
 pub use extrinsic_weights::constants::ExtrinsicBaseWeight;
-pub use paritydb_weights::constants::ParityDbWeight;
 pub use rocksdb_weights::constants::RocksDbWeight;