Revert "Manual backport for datetime-diff function for vertica #26816"

[calherries]

Reverts #27066. Backporting this was my mistake. Point releases are for bug and security fixes.
See this comment for more context #27074 (review)

[codecov]

Codecov Report

Base: 64.36% // Head: 64.36% // No change to project coverage 👍

Coverage data is based on head (10586b8) compared to base (a9803fa).
Patch has no changes to coverable lines.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-x.45.x   #27222   +/-   ##
===============================================
  Coverage           64.36%   64.36%           
===============================================
  Files                3167     3167           
  Lines               93025    93025           
  Branches            11791    11791           
===============================================
  Hits                59872    59872           
  Misses              28419    28419           
  Partials             4734     4734           

Flag	Coverage Δ
back-end	85.48% <ø> (ø)

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