STR-1996: Flexi Test Bridge node restart and other misc updates

[MdTeach]

Description

• Add a bridge node restart test
• Simplify test execution by supporting both:
  • ./run_test.sh fn_rpc_test
  • ./run_test.sh ./tests/fn_rpc_test.py
• When CI functional tests fail, upload only logs instead of the entire __dd directory
• Update the Functional Tests README

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature/Enhancement (non-breaking change which adds functionality or enhances an existing one)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor
• New or updated tests
• Dependency Update

Notes to Reviewers

Checklist

• I have performed a self-review of my code.
• I have commented my code where necessary.
• I have updated the documentation if needed.
• My changes do not introduce new warnings.
• I have added (where necessary) tests that prove my changes are effective or that my feature works.
• New and existing tests pass with my changes.
• I have disclosed my use of AI in the body of this PR.

Related Issues

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.40%. Comparing base (bfabf2a) to head (df24e4d).

@@            Coverage Diff             @@
##             main     #313      +/-   ##
==========================================
+ Coverage   70.33%   70.40%   +0.06%     
==========================================
  Files         171      171              
  Lines       23927    23927              
==========================================
+ Hits        16830    16846      +16     
+ Misses       7097     7081      -16     

see 11 files with indirect coverage changes

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