[CBR-96] Remove orphaned Bi instances

[coot]

Description

This PR removes orphened Bi instances from core. This is split from my work on CBR-96.

Linked issue

Type of change

• 🐞 Bug fix (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 change)
• 🏭 Refactoring that does not change existing functionality but does improve things like code readability, structure etc
• 🔨 New or improved tests for existing code
• ⛑ git-flow chore (backport, hotfix, etc)

Developer checklist

• I have read the style guide document, and my code follows the code style of this project.
• If my code deals with exceptions, it follows the guidelines.
• I have updated any documentation accordingly, if needed. Documentation changes can be reflected in opening a PR on cardanodocs.com, amending the inline Haddock comments, any relevant README file or one of the document listed in the docs directory.

Testing checklist

• I have added tests to cover my changes.
• All new and existing tests passed.

QA Steps

Screenshots (if available)

[erikd]

From the build logs:

src/Pos/Binary.hs:12:1: error:
    Could not find module ‘Pos.Binary.Merkle’
    Perhaps you meant Pos.Binary.Core (from cardano-sl-core-1.3.0)
    Use -v to see a list of the files searched for.
   |
12 | import Pos.Binary.Merkle ()

[erikd]

Looks reasonable. Glad to see some redundant constraints being removed as well.

[coot]

Thanks @erikd!