Call the syncdb management command inside lambda handler

[aloftus23]

🗣 Description

Call the syncdb management command inside lambda handler instead of repeating the same same code.

The management command was only used for local and then there was a mirrored script for the producion lambda. Instead, the production lambda will call the local script.

💭 Motivation and context

Repetitive code can cause a lot of issues. Fro example, someone fixes syncdb on the local version, but then doesn't update the actual lambda call.

🧪 Testing

Passes pre-commit and github checks.

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All future TODOs are captured in issues, which are referenced
  in code comments.
• All relevant type-of-change labels have been added.
• I have read the CONTRIBUTING document.
• These code changes follow cisagov code standards.
• All relevant repo and/or project documentation has been updated
  to reflect the changes in this PR.
• Tests have been added and/or modified to cover the changes in this PR.
• All new and existing tests pass.

✅ Pre-merge checklist

• Revert dependencies to default branches.
• Finalize version.

✅ Post-merge checklist

• Create a release.

[cduhn17]

LGTM

[rapidray12]

Simple enough