Fix PQ Integration tests

[alexw91]

Issues:

N/A

Description of changes:

The BoringSSL command moved from ${SCRATCH_FOLDER}/boring-ssl-build/tool/bssl to ${SCRATCH_FOLDER}/boring-ssl-build/bssl.

This PR updates the PQ integration tests to validate that required binaries are present before attempting to use them.

Call-outs:

None

Testing:

Tested locally on Ubuntu 22.04 LTS release.

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

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.75%. Comparing base (ef71b09) to head (30829dd).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2392      +/-   ##
==========================================
- Coverage   78.77%   78.75%   -0.02%     
==========================================
  Files         620      620              
  Lines      107961   107961              
  Branches    15329    15331       +2     
==========================================
- Hits        85046    85029      -17     
- Misses      22258    22274      +16     
- Partials      657      658       +1     

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