feat: add a few robustness-es features around htx submission

[mfontanini]

This adds 2 things:

• We wait for caddy to generate the TLS certificate before submitting the first HTX. If we don't do this, then the first one would always fail since the verifiers have no way to fetch the attestation report, since our cert isn't generated yet.
• Enables the gas estimation filler in the eth provider, to make gas estimation less likely to fail (allegedly? we've seen this failing in other places).