Silences Pip Install Messages in Code Executors

[WaelKarkoub]

Why are these changes needed?

Related issue number

Closes #2075

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 70.00000% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 46.79%. Comparing base (fafc29e) to head (efac097).

Files	Patch %	Lines
autogen/coding/utils.py	78.57%	1 Missing and 2 partials ⚠️
autogen/coding/jupyter/jupyter_code_executor.py	0.00%	2 Missing ⚠️
autogen/coding/docker_commandline_code_executor.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2105      +/-   ##
==========================================
+ Coverage   36.90%   46.79%   +9.88%     
==========================================
  Files          68       68              
  Lines        7061     7069       +8     
  Branches     1541     1671     +130     
==========================================
+ Hits         2606     3308     +702     
+ Misses       4225     3477     -748     
- Partials      230      284      +54     

Flag	Coverage Δ
unittests	46.66% <70.00%> (+9.76%)	⬆️

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[ekzhu]

Can you add unit tests to check for the expected behavior?

1. input code block contains pip install, package is valid, output is empty
2. input code block contains pip install, package is invalid, etc. random strings, output contains error.

See the existing unit tests for jupyter code executor for reference.