[cumulus] parachains-common testnet constants cleaning (#3134)

The `parachains-common` contains a lots of constants and type
definitions which are used for `polkadot-sdk`'s testnet runtimes and
also for `polkadot-fellows`'s production [SP
runtimes](https://github.com/polkadot-fellows/runtimes/tree/main/system-parachains/constants).
This PR cleans `parachains-common` module to contain only common and
generic functionality.

Testnet-specific constants have been moved to the separate module
dedicated just for testnets:
`polkadot-sdk/cumulus/parachains/runtimes/constants/`


Part of: https://github.com/paritytech/polkadot-sdk/issues/3054

---------

Co-authored-by: georgepisaltu <george.pisaltu@parity.io>

cumulus/parachains/runtimes/collectives/collectives-westend/src/lib.rs

@@ -83,12 +83,14 @@ pub use parachains_common as common;
 use parachains_common::{
 	impls::{DealWithFees, ToParentTreasury},
 	message_queue::*,
-	westend::{account::*, consensus::*, currency::*, fee::WeightToFee},
 	AccountId, AuraId, Balance, BlockNumber, Hash, Header, Nonce, Signature,
 	AVERAGE_ON_INITIALIZE_RATIO, DAYS, HOURS, MAXIMUM_BLOCK_WEIGHT, MINUTES, NORMAL_DISPATCH_RATIO,
 	SLOT_DURATION,
 };
 use sp_runtime::RuntimeDebug;
+use testnet_parachains_constants::westend::{
+	account::*, consensus::*, currency::*, fee::WeightToFee,
+};
 use xcm_config::{
 	GovernanceLocation, LocationToAccountId, TreasurerBodyId, XcmOriginToTransactDispatchOrigin,
 };