fix: Hide autosuggest results text when not relevant

[gethinwebster]

Description

Some adjustments to autosuggest:

• Hide the filteringResultsText when the input text isn't being used to filter results (i.e. when first opening an autosuggest with an existing value)
• Update the docs with more information about the filteringResultsText arguments

Related links, issue #, if available: AWSUI-61278

How has this been tested?

Updated unit tests

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 97.16%. Comparing base (188a370) to head (55f85b1).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3914   +/-   ##
=======================================
  Coverage   97.16%   97.16%           
=======================================
  Files         850      850           
  Lines       24779    24779           
  Branches     8734     8733    -1     
=======================================
  Hits        24076    24076           
- Misses        654      696   +42     
+ Partials       49        7   -42     

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[gethinwebster]

unfortunately actually fixing this isn't really an option, as there are already a number of teams who do this subtraction already, so changing this behavior would be a breaking change