fix(config): Correctly serialize testnet parameters into toml config format

[arya2]

Motivation

This PR correctly serializes testnet parameters into the toml config format.

Closes #8920.

Solution

Converts Config to DConfig before serializing.

Tests

Adds a roundtrip serialization test.

Follow-up Work

Add an acceptance test for #9201.

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.

[oxarbitrage]

Looks good, thanks!

[mergify]

This pull request has been removed from the queue for the following reason: checks failed.

The merge conditions cannot be satisfied due to failing checks:

• ❌ Unit tests / Test integration with lightwalletd
• ☑️ Build CD Docker / Build images
• ☑️ Get disk name / Get Mainnet cached disk
• ☑️ Test CD custom Docker config file / Test custom-conf in Docker
• ☑️ Test CD default Docker config file / Test default-conf in Docker
• ☑️ Test CD testnet Docker config file / Test testnet-conf in Docker

You should look at the reason for the failure and decide if the pull request needs to be fixed or if you want to requeue it.

If you want to requeue this pull request, you need to post a comment with the text: @mergifyio requeue

[arya2]

@Mergifyio refresh

[mergify]

refresh

✅ Pull request refreshed

[mergify]

This pull request has been removed from the queue for the following reason: checks failed.

The merge conditions cannot be satisfied due to failing checks:

• ❌ Unit tests / Test integration with lightwalletd
• ☑️ Build CD Docker / Build images
• ☑️ Get disk name / Get Mainnet cached disk
• ☑️ Test CD custom Docker config file / Test custom-conf in Docker
• ☑️ Test CD default Docker config file / Test default-conf in Docker
• ☑️ Test CD testnet Docker config file / Test testnet-conf in Docker

You should look at the reason for the failure and decide if the pull request needs to be fixed or if you want to requeue it.

If you want to requeue this pull request, you need to post a comment with the text: @mergifyio requeue

[arya2]

@Mergifyio refresh

[mergify]

refresh

✅ Pull request refreshed

[mergify]

This pull request has been removed from the queue for the following reason: checks failed.

The merge conditions cannot be satisfied due to failing checks:

• ❌ Unit tests / Test integration with lightwalletd
• ☑️ Build CD Docker / Build images
• ☑️ Get disk name / Get Mainnet cached disk
• ☑️ Test CD custom Docker config file / Test custom-conf in Docker
• ☑️ Test CD default Docker config file / Test default-conf in Docker
• ☑️ Test CD testnet Docker config file / Test testnet-conf in Docker

You should look at the reason for the failure and decide if the pull request needs to be fixed or if you want to requeue it.

If you want to requeue this pull request, you need to post a comment with the text: @mergifyio requeue

[arya2]

@Mergifyio refresh

[mergify]

refresh

✅ Pull request refreshed