fix: spectrum textfield validation icon position with set content-box

[dsmmcken]

Moves a DHE fix to DHC.

fixes text field spectrum validation icon position:

BREAKING CHANGE: the duplicate spectrum-Textfield-validationIcon css in DHE should be removed

[dsmmcken]

feels like a bit of an abuse of breaking change, but not sure how else to flag that the DHE code can be removed when this is merged to DHE.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.11%. Comparing base (677e4c5) to head (6c01feb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1825   +/-   ##
=======================================
  Coverage   46.11%   46.11%           
=======================================
  Files         628      628           
  Lines       37822    37822           
  Branches     9529     9529           
=======================================
  Hits        17440    17440           
  Misses      20328    20328           
  Partials       54       54           

Flag	Coverage Δ
unit	46.11% <ø> (ø)

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[bmingles]

Looks like e2e tests need to be updated

[dsmmcken]

Flaky test failure, re-ran and it passed.

[bmingles]

LGTM. Verified that the icon is positioned correctly in the styleguide y setting validationState="invalid"