Adding handle for missing unique field key in AdoFields

[nharper285]

Summary of the Pull Request

What is this about?

PR Checklist

• Applies to work item: Missing UniqueFields key in AdoFields notification config is not handled.  #2984
• CLA signed. If not, go over here and sign the CLI.
• Tests added/passed
• Requires documentation to be updated
• I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx

Info on Pull Request

What does this include?
Resolving bug #2984 by adding exception handling.

Validation Steps Performed

How does someone test & validate?

[codecov-commenter]

Codecov Report

Merging #2986 (b2128b1) into main (947bb7f) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #2986      +/-   ##
==========================================
- Coverage   29.02%   29.02%   -0.01%     
==========================================
  Files         304      304              
  Lines       36300    36302       +2     
==========================================
  Hits        10535    10535              
- Misses      25765    25767       +2     

Impacted Files	Coverage Δ
...Service/ApiService/onefuzzlib/notifications/Ado.cs	0.00% <0.00%> (ø)

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