Fix issues in handling metadata values

[Nuvindu]

Purpose

$subject

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.02%. Comparing base (796f2b7) to head (3ec0df2).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
ballerina/utils.bal	81.81%	4 Missing ⚠️
ballerina/vector_store.bal	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #17      +/-   ##
==========================================
- Coverage   77.20%   77.02%   -0.18%     
==========================================
  Files           2        2              
  Lines         193      222      +29     
  Branches       69       81      +12     
==========================================
+ Hits          149      171      +22     
- Misses         44       51       +7     

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