Update Symphony chain.json chain-id to testnet-4

[cmancrypto]

No description provided.

[ankurdotb]

The edits as-is are fine but there can be some improvements:

1. The chain.json file typically contains URLs to genesis file. I can see this in the Github repo, but the chain.json currently provides it as https://rpc.testnet.symphonychain.org/genesis. This is not a static URL to the genesis file, and did in fact time our with an error. (Hence why the static URL to that that file is better, than a proxy endpoint like it currently has.)
2. Take a look at the associated version.json file as well and update accordingly.

[cmancrypto]

Thank you for the review - all should be addressed now.

[cmancrypto]

Thank you for correcting this, I appreciate your help and feedback.