fix prysm rpc provider & gateway flags

[Marketen]

fixes error:
time="2024-07-23 08:14:36" level=warning msg="Could not determine if beacon chain started" error="could not receive ChainStart from stream: could not setup beacon chain ChainStart streaming client: rpc error: code = Unavailable desc = connection error: desc = "transport: Error while dialing: dial tcp: address http://beacon-chain.prysm-holesky.dappnode:4000: too many colons in address": could not connect: could not connect" prefix=client

from prysm cli docs:
https://docs.prylabs.network/docs/prysm-usage/parameters#validator-flags

--beacon-rest-api-provider value                   Beacon node REST API provider endpoint. (default: "http://127.0.0.1:3500")
--beacon-rpc-gateway-provider value                Beacon node RPC gateway provider endpoint. (default: "127.0.0.1:3500")
--beacon-rpc-provider value                        Beacon node RPC provider endpoint. (default: "127.0.0.1:4000")

beacon-rpc-gateway-provider value && beacon-rpc-provider value should not have "http://"