sTPS Helm chart should support parallelism parameters for sender binary

[bredamatt]

As of https://github.com/paritytech/polkadot-stps/pull/70

the sender binary now supports running in parallel. This means the sender Pod does not need to be replicated, but can instead run in parallel. This way we can more easily fill blocks as we are signing and submitting transactions faster.

The parameters are as follows:

$ ./target/release/sender --help
Util program to send transactions

Usage: sender [OPTIONS] --node-url <NODE_URL> --num <NUM>

Options:
      --node-url <NODE_URL>            Node URL. Can be either a collator, or relaychain node based on whether you want to measure parachain TPS, or relaychain TPS
      --threads <THREADS>              Set to the number of desired threads (default: 1). If set > 1 the program will spawn multiple threads to send transactions in parallel [default: 1]
      --sender-index <SENDER_INDEX>    The sender index. Useful if you set threads to =< 1 and run multiple sender instances (as in the zombienet tests)
      --total-senders <TOTAL_SENDERS>  Total number of senders
      --chunk-size <CHUNK_SIZE>        Chunk size for sending the extrinsics [default: 50]
      --num <NUM>                      Total number of pre-funded accounts (on funded-accounts.json)
  -h, --help                           Print help
  -V, --version                        Print version

Required parameters:

• node-url
• num

Usage:

• If threads is set to <= 1, then sender-index should be set to based on how many replicas of the sender is deployed
• The number of replicas deployed is equal to total-senders.
• If threads is set to > 1 then total-senders and sender-index does not have to be set.

[BulatSaif]

@bredamatt is it still needed?