chore(otlp-grpc-exporter): update TLS certs and keys for tests

[llc1123]

Which problem is this PR solving?

The tests are failing because of expired certs.

Short description of the changes

Updated the certs and keys.

Also remove unused certs in other tests.

Type of change

Please delete options that are not relevant.

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

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Existing tests

Checklist:

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

[codecov]

Codecov Report

Merging #3878 (57d5847) into main (51dd6f2) will increase coverage by 0.76%.
The diff coverage is n/a.

❗ Current head 57d5847 differs from pull request most recent head 6e0dc59. Consider uploading reports for the commit 6e0dc59 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3878      +/-   ##
==========================================
+ Coverage   92.20%   92.97%   +0.76%     
==========================================
  Files         145      300     +155     
  Lines        3452     9104    +5652     
  Branches      711     1862    +1151     
==========================================
+ Hits         3183     8464    +5281     
- Misses        269      640     +371     

see 171 files with indirect coverage changes