Adjust chains names and ids to the multi-runtime realm before the next testnet restart

[ekovalev]

In order to be able to load the chain spec from a JSON file and ensure the client was compiled against the correct runtime, we need to stick to chains naming convention:

• chain ID must have a prefix corresponding to the runtime, e.g. gear_dev, gear_local, vara_staging_testnet etc.

For the meantime (as of 2022-08-10) we kept the current staging chain id intact and fiddled with the service code to attribute this name to the gear runtime even though it doesn't have a prefix to avoid another testnet restart from genesis only a week after the last restart. However, this has to be corrected sooner rather than later.