SNOW-1757822: Exclude directories from shaded packages check

[sfc-gh-dheyman]

Overview

SNOW-1757822

Pre-review self checklist

• PR branch is updated with all the changes from master branch
• The code is correctly formatted (run mvn -P check-style validate)
• New public API is not unnecessary exposed (run mvn verify and inspect target/japicmp/japicmp.html)
• The pull request name is prefixed with SNOW-XXXX:
• Code is in compliance with internal logging requirements

External contributors - please answer these questions before submitting a pull request. Thanks!

1. What GitHub issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Issue: #NNNN

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
   • I am adding new logging messages
   • I am modifying authorization mechanisms
   • I am adding new credentials
   • I am modifying OCSP code
   • I am adding a new dependency or upgrading an existing one
   • I am adding new public/protected component not marked with @SnowflakeJdbcInternalApi (note that public/protected methods/fields in classes marked with this annotation are already internal)

3. Please describe how your code solves the related issue.

   Please write a short description of how your code change solves the related issue.