BFD-3315: pg_repack bug fixes and updated readme

[keithdadkins]

JIRA Ticket:
BFD-3315

User Story or Bug Summary:

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What Does This PR Do?

Replace me.

What Should Reviewers Watch For?

If you're reviewing this PR, please check for these things in particular:

• Verify all PR security questions and checklists have been completed and addressed.

What Security Implications Does This PR Have?

Submitters should complete the following questionnaire:

• If the answer to any of the questions below is Yes, then you must supply a link to the associated Security Impact Assessment (SIA), security checklist, or other similar document in Confluence here: N/A

  • Does this PR add any new software dependencies?
    • Yes
    • No
  • Does this PR modify or invalidate any of our security controls?
    • Yes
    • No
  • Does this PR store or transmit data that was not stored or transmitted before?
    • Yes
    • No

• If the answer to any of the questions below is Yes, then please add @StewGoin as a reviewer, and note that this PR should not be merged unless/until he also approves it.

  • Do you think this PR requires additional review of its security implications for other reasons?
    • Yes
    • No

What Needs to Be Merged and Deployed Before this PR?

This PR cannot be either merged or deployed until the following prerequisite changes have been fully deployed:

• N/A

Submitter Checklist

I have gone through and verified that...:

• I have named this PR and branch so they are automatically linked to the (most) relevant Jira issue. Ie: BFD-123: Adds foo
• This PR is reasonably limited in scope, to help ensure that:
  1. It doesn't unnecessarily tie a bunch of disparate features, fixes, refactorings, etc. together.
  2. There isn't too much of a burden on reviewers.
  3. Any problems it causes have a small "blast radius".
  4. It'll be easier to rollback if that becomes necessary.
• This PR includes any required documentation changes, including README updates and changelog / release notes entries.
• The data dictionary has been updated with any field mapping changes, if any were made.
• All new and modified code is appropriately commented, such that the what and why of its design would be reasonably clear to engineers, preferably ones unfamiliar with the project.
• All tech debt and/or shortcomings introduced by this PR are detailed in TODO and/or FIXME comments, which include a JIRA ticket ID for any items that require urgent attention.
• Reviews are requested from both:
  • At least two other engineers on this project, at least one of whom is a senior engineer or owns the relevant component(s) here.
  • Any relevant engineers on other projects (e.g. DC GEO, BB2, etc.).
• Any deviations from the other policies in the DASG Engineering Standards are specifically called out in this PR, above.
  • Please review the standards every few months to ensure you're familiar with them.