Add syncing metagraph and remove manual script

[stephen-ridges]

• Still uses the JSON file as a cache to see if a hotkey is registered
• fallback to polling every 15 minutes

Command to get current registered hotkeys:

rsync -chavzP --stats ubuntu@mainnet-platform:/home/ubuntu/ridges/subnet_hotkeys_cache.json ./subnet_hotkeys_cache.json

Local testing

Setup localnet here

NEW_MINER=miner-7
btcli wallet create --wallet-name "${NEW_MINER}" --no-use-password --n-words 12 --wallet-path ~/.bittensor/wallets/ --hotkey default
btcli wallet transfer --wallet.name owner --dest "$(jq --raw-output ".ss58Address" ~/.bittensor/wallets/"${NEW_MINER}"/coldkeypub.txt)" --amount 1000 --no_prompt
btcli subnet register --wallet.name "${NEW_MINER}" --netuid 1 --wallet.hotkey default --subtensor.chain_endpoint ws://127.0.0.1:9944 --no-prompt