fix: Prevent height hook from running in token-mode when value prop changes

[ernst-dev]

Description

When providing both value and tokens, updating the value prop results in the adjustHeight hook running and affecting the caret position. This PR separates the useEffect so it can run independently when in either mode, this way value updates don't affect token mode and vice versa.

Related links, issue #, if available: AWSUI-61987

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.42%. Comparing base (1cfdac5) to head (169de5b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4513   +/-   ##
=======================================
  Coverage   97.42%   97.42%           
=======================================
  Files         936      936           
  Lines       29615    29616    +1     
  Branches    10761    10760    -1     
=======================================
+ Hits        28851    28852    +1     
- Misses        716      757   +41     
+ Partials       48        7   -41     

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