feat: remove create option when empty searchString

[jake-bassett]

Description

Removes the "Create" option when no search text is provided.

[codecov]

Codecov Report

Merging #859 (b480e33) into main (0495b2d) will decrease coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #859      +/-   ##
==========================================
- Coverage   85.47%   85.41%   -0.06%     
==========================================
  Files         797      797              
  Lines       16351    16356       +5     
  Branches     1955     1958       +3     
==========================================
- Hits        13976    13971       -5     
- Misses       2343     2353      +10     
  Partials       32       32              

Impacted Files	Coverage Δ
...ts/components/src/combo-box/combo-box.component.ts	83.10% <100.00%> (-6.41%)	⬇️

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[github-actions]

Unit Test Results

    4 files  ±0  252 suites  ±0   14m 51s ⏱️ -30s
908 tests ±0  908 ✔️ ±0  0 💤 ±0  0 ❌ ±0 
914 runs  ±0  914 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit ee7bd72. ± Comparison against base commit 0495b2d.