docs: enhance cypress testing documentation with troubleshooting and …

Fixes #9657

- Add comprehensive table of contents for better navigation
- Include detailed environment configuration section with examples
- Add extensive troubleshooting section with common issues and solutions
- Include best practices for writing maintainable tests
- Improve folder structure documentation with clear explanations
- Add step-by-step guides for adding new connectors and test scenarios
- Include multiple ways to run tests (interactive, headless, specific suites)
- Add debug mode instructions and help resources
- Enhance credentials file documentation with auth type explanations
- Overall improvement in readability and organization for contributors

## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [x] Documentation
- [ ] CI/CD

## Description
Enhanced the Cypress testing documentation (cypress-tests-v2/README.md) to improve the contributor experience and make it easier for new developers to set up and run tests.

**Key improvements:**
- Added comprehensive table of contents for better navigation
- Included detailed environment configuration section with multiple setup options
- Added extensive troubleshooting section covering 6 common issues with solutions
- Included best practices guide for writing maintainable tests
- Improved folder structure documentation with clear explanations
- Added step-by-step guides for adding new connectors and test scenarios
- Documented multiple ways to run tests (interactive mode, headless, specific suites)
- Added debug mode instructions and help resources
- Enhanced credentials file documentation with auth type explanations
- Overall improvement in readability and organization



### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
This documentation improvement addresses the need for better onboarding of new contributors to the Cypress testing suite. The previous README was functional but lacked:
- Troubleshooting guidance for common setup issues
- Best practices for writing tests
- Clear examples for adding new connectors
- Comprehensive environment setup instructions


## How did you test it?
- Reviewed the documentation for clarity and completeness
- Verified all code examples use correct syntax
- Ensured all links and references are accurate
- Confirmed the markdown renders properly
- Validated that the troubleshooting steps address real issues developers encounter



## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all` (N/A - documentation only)
- [x] I addressed lints thrown by `cargo clippy` (N/A - documentation only)
- [x] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible (N/A - documentation only)


<think>
PR Context:
- Title: docs: enhance cypress testing documentation with troubleshooting and …
- Merged: None
- Files changed: 2 files
- Commits: 2 commits

Implementation approach:
Fixes #9657

- Add comprehensive table of contents for better navigation
- Include detailed environment configuration section with examples
- Add extensive troubleshooting section with common issues and solutions
- Include best practices for writing maintainable tests
- Improve folder structure documentation with clear explanations
- Add step-by-step guides for adding new connectors and test scenarios
- Include multiple ways to run tests (interactive, headless, specific suites)
- Add de
</think>

To implement this, you'll need to modify:


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