fix: remove extra closing parenthesis in sub-config error

[rogercoll]

Description

Removed an extra closing parenthesis. This corrects the formatting of the error message for unexpected sub-config value kinds.

Found in: https://github.com/open-telemetry/opentelemetry-collector-contrib/pull/33268/files#diff-9137db5fde5eb0d6870425c0023cec1a5bdfe92f58f8a72e278b55635afc6e95R48

Link to tracking issue

Testing

Documentation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 92.34%. Comparing base (a082f2e) to head (15870f5).

Files	Patch %	Lines
confmap/confmap.go	0.00%	1 Missing :warning:

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10479   +/-   ##
=======================================
  Coverage   92.34%   92.34%           
=======================================
  Files         393      393           
  Lines       18621    18621           
=======================================
  Hits        17196    17196           
  Misses       1068     1068           
  Partials      357      357           

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[rogercoll]

Added a changelog entry in case other the tests of confmap users start to fail with the new release.