Respect original stream metadata

[khoaanguyenn]

Problem

The pipelinewise tap disregards the original stream and runs refresh schema every time Meltano run command is executed. Thus, it overrides the original stream with the newly refreshed schema, wiping out metadata.selected fields that is being used to disable a particular column

Proposed changes

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• Bugfix (non-breaking change which fixes an issue)
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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
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• Relevant documentation is updated including usage instructions

[khoaanguyenn]

1. This original code doesn't respect metadata within the catalog provided by Meltano SDK, it's overridden by the new discovery stream from Postgres catalog every time it's executed. The above rectification retains the original selected field in each stream that is required to select the corresponding columns per configuration in Meltano YAML file.