Mailchimp: Elements don't respect block gap

### Impacted plugin

Jetpack

### Quick summary

This is how it appears with TT3.


The gaps between the elements are specified in the block and it seems random `1em`. It should, at least respect the block gap, and it'd be better if it the block gap is customisable in Global Styles.

cc: @jeffikus

### Steps to reproduce

1. Add the mailchimp block

### A clear and concise description of what you expected to happen.

_No response_

### What actually happened

_No response_

### Impact

All

### Available workarounds?

Yes, difficult to implement

### Platform (Simple and/or Atomic)

_No response_

### Logs or notes

_No response_

Start by reproducing the Mailchimp block with the TT3 theme and compare the element spacing with the block gap shown in the issue. Trace the Mailchimp block entry point and determine how its spacing is set. Done means the elements respect the configured block gap and the result is verified against the reported layout.

Written by the indexing model from the issue text.