test(otlp-grpc-exporter-base): remove duplicated delete statements

[cjihrig]

Which problem is this PR solving?

There are duplicated delete statements in some of the test cleanup code in otlp-grpc-exporter-base. You can see in the diff that the duplicated statements were immediately following each other.

Fixes # N/A

Short description of the changes

This commit removes the duplicated delete statements.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Existing test suite.

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.01%. Comparing base (6854413) to head (0a610cc).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6022   +/-   ##
=======================================
  Coverage   95.01%   95.01%           
=======================================
  Files         313      313           
  Lines        8799     8799           
  Branches     1888     1888           
=======================================
  Hits         8360     8360           
  Misses        439      439           

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[pichlermarc]

thanks!

[otelbot]

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