fix: agent evaluations detailed output rows wrapping issue

[nimanthadilz]

Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Closes: Agent Evaluator print_detailed_results output is not readable #3363
• This PR sets a max column width for the table printed in detailed output of agent evaluations.

Problem:
The detailed output of agent evaluations is not readable due to rows in the table getting wrapped. This happens when there are long text values in cells.

Solution:
Existing code uses tabulate python package to format the table. We can set a maximum column width using maxcolwidths parameter. I have set it to 25.

After the fix:

Testing Plan

I have manually tested if the output is properly displayed after changes. Please let me know if any unit tests can be added for this.

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Manual End-to-End (E2E) Tests:

1. Create a simple agent using adk (preferably an agent that outputs a long text).
2. Create an evalset for this agent.
3. Run the evalset with print_detailed_results option and check if the output is properly displayed.

If you want a quick setup for testing this, I have a sample repo with an agent and an evalset here. You will have to manually build & install the fixed adk version to test it.

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

[adk-bot]

Thank you @nimanthadilz for your contribution! 🎉

Your changes have been successfully imported and merged via Copybara in commit 4284c61.

Closing this PR as the changes are now in the main branch.