tracking(sidecar): remove leftover TODO comments

[merklefruit]

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1. Driver: match when we have more request types
2. Driver: fix retry logic, and move to separate task in constraints client
3. primitives::*: minor nits and SSZ-related implementation choices
4. Config: parse validator indexes from a file: Are we still using these? if so, add this, else remove completely
5. StateFetcher: add block number in params
6.  ExecutionState: add a way to add validation params via CLI
7.  ExecutionState: also validate more conditions from Reth
8. ConsensusState: integrate onchain registry in request validation
9. ConsensusState: check if the sidecar is scheduled to propose (?)
10. Chainio: related to https://github.com/chainbound/bolt/issues/343
11. Chainio: performance nerdsnipe?
12. Chainio: check if this can be cleaned up a little
13. Builder API: determine adequate timeout value
14. Builder API: this should be removed as it's not done in the sidecar anymore, IMO
15. Builder API: handle get_header failure more clearly
16. Builder API: handle get_payload failure more clearly
17. Builder API: add some more sanity checks when checking for local payload integrity