Fix table_cache when disable_table_cache is set to True

[josescuderoh]

Problem

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When setting disable_table_cache to True the target throws the following error when trying to retrieve the file_format_type from the db object.

UnboundLocalError: local variable 'db' referenced before assignment

Proposed changes

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If it fixes a bug or resolves a feature request, be sure to link to that issue.

With this change, we define the db object outside of the if statement to avoid the above error. We also set the default value of table_cache=None as defined in persist_lines and DbSync class.

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• Description above provides context of the change
• I have added tests that prove my fix is effective or that my feature works
• Unit tests for changes (not needed for documentation changes)
• CI checks pass with my changes
• Bumping version in setup.py is an individual PR and not mixed with feature or bugfix PRs
• Commit message/PR title starts with [AP-NNNN] (if applicable. AP-NNNN = JIRA ID)
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• Relevant documentation is updated including usage instructions

[josescuderoh]

@jeet-parekh-wise @Samira-El @louis-pie would it be possible for you to review this small fix?