haskell.packages.ghc881.unordered-containers: remove broken override

[vaibhavsagar]

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @

[cdepillabout]

@GrahamcOfBorg build haskell.packages.ghc881.unordered-containers

[cdepillabout]

@vaibhavsagar Should this PR and your other recent PRs (#67651, #67653, #67654, #67655, and #67657) be based on the haskell-updates branch instead of master?

@infinisil recently left a comment explaining that any change to the configuration-*.nix files should probably go to the haskell-updates branch.

[vaibhavsagar]

Closed in favour of #67709.