chore(toolkit-lib): improve CCAPI context provider error handling

[mrgrain]

Just noticed some missed opportunities in the error handling for the CCAPI provider.

This only has limited end-user impact:

• instead of error: cause it's now error\ncause
• Some not enough results found error messages now include the expectation

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.00%. Comparing base (49699d8) to head (fdc562e).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #570      +/-   ##
==========================================
- Coverage   79.61%   79.00%   -0.61%     
==========================================
  Files          47       47              
  Lines        7083     7083              
  Branches      798      791       -7     
==========================================
- Hits         5639     5596      -43     
- Misses       1423     1468      +45     
+ Partials       21       19       -2     

Flag	Coverage Δ
suite.unit	79.00% <ø> (-0.61%)	⬇️

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