Convert chainspec to raw (#4057)

The plain `people-kusama` and `coretime-kusama` chainspecs were uploaded
at https://github.com/paritytech/polkadot-sdk/pull/3961. Only binaries
with compatible runtime versions can run with plain chainspec. For
example:

One of the latest master builds fails:

```
docker run paritypr/polkadot-parachain-debug:master-216509db --chain coretime-kusama
...
Error: Service(Client(Storage("wasm call error Other: Exported method GenesisBuilder_get_preset is not found"))
```

Master build from 5 days ago:

```
docker run paritypr/polkadot-parachain-debug:master-68cdb126 --chain coretime-kusama
...
2024-04-08 16:51:02 [Parachain]  Initializing Genesis block/state (state: 0xc418…889c, header-hash: 0x638c…d050)
2024-04-08 16:51:03 [Relaychain]  Initializing Genesis block/state (state: 0xb000…ef6b, header-hash: 0xb0a8…dafe)
2024-04-08 16:51:03 [Relaychain]  Loading GRANDPA authority set from genesis on what appears to be first startup.
2024-04-08 16:51:03 [Relaychain]  Creating empty BABE epoch changes on what appears to be first startup.
2024-04-08 16:51:03 [Relaychain]  Local node identity is: 12D3KooWQEp2uPow3FnngGmy9dYQ3qxY1GkmumS5MqBWEQscwTyy
2024-04-08 16:51:03 [Relaychain]  Highest known block at #0
...
```

## Changes:

1. Rename:
```
coretime-kusama.json -> coretime-kusama-genesis.json
people-kusama.json -> people-kusama-genesis.json
```

2. Generate raw chainspec:

```
docker run --rm -v $(pwd):/dir paritypr/polkadot-parachain-debug:master-68cdb126 build-spec --raw --chain /dir/people-kusama-genesis.json > people-kusama.json 
docker run --rm -v $(pwd):/dir paritypr/polkadot-parachain-debug:master-68cdb126 build-spec --raw --chain /dir/coretime-kusama-genesis.json > coretime-kusama.json
```

## Tests:

New chainspec can run on the latest master build:

```
docker run -it --rm -v $(pwd):/dir paritypr/polkadot-parachain-debug:master-216509db --chain /dir/coretime-kusama.json
...
2024-04-09 16:44:39 [Relaychain] ️ Syncing, target=#22665488 (8 peers), best: #2371 (0x19f8…5f3a), finalized #2048 (0xede6…f879),  388.6kiB/s  87.0kiB/s
2024-04-09 16:44:39 [Parachain]  Idle (6 peers), best: #0 (0x638c…d050), finalized #0 (0x638c…d050),  6.3kiB/s  2.8kiB/s
```

Plain chainspec will fail:

```
docker run -it --rm -v $(pwd):/dir paritypr/polkadot-parachain-debug:master-216509db --chain /dir/coretime-kusama-genesis.json
... 
Error: Service(Client(Storage("wasm call error Other: Exported method GenesisBuilder_get_preset is not found")))
```