[CHORE] Update lerna and remove issue_handler tool folder

[sbarrio]

What does this PR do?

This PR updates lerna to 9.0.7 (which solves some security issues raised by dependabot).

It also removes the issue_handler tool folder, which should have been removed alongside the Github action for the issue notification workflow.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)
• If this PR is auto-generated, please make sure also to manually update the code related to the change

[Copilot]

Pull request overview

Updates monorepo tooling dependencies (primarily Lerna) to address security findings, and removes the obsolete tools/issue_handler utility that should have been deleted with its GitHub Action workflow.

Changes:

• Bump lerna from 9.0.5 to 9.0.7 and refresh yarn.lock accordingly
• Add a Yarn resolutions override for handlebars to enforce >=4.7.9
• Remove the tools/issue_handler tool source, tests, and related scripts/docs

Reviewed changes

Copilot reviewed 19 out of 20 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
yarn.lock	Updates lockfile to reflect lerna@9.0.7 and associated dependency graph/security-related bumps.
package.json	Bumps lerna devDependency and adds handlebars resolution (>=4.7.9).
tools/issue_handler/tests/test_slack_handler.py	Removes deleted tool’s unit tests.
tools/issue_handler/tests/test_openai_handler.py	Removes deleted tool’s unit tests.
tools/issue_handler/tests/test_github_handler.py	Removes deleted tool’s unit tests.
tools/issue_handler/test_slack_webhook.py	Removes deleted tool’s local webhook test script.
tools/issue_handler/test_local.py	Removes deleted tool’s local test script.
tools/issue_handler/src/slack_handler.py	Removes Slack posting implementation for deleted tool.
tools/issue_handler/src/openai_handler.py	Removes OpenAI analysis implementation for deleted tool.
tools/issue_handler/src/github_handler.py	Removes GitHub issue fetching implementation for deleted tool.
tools/issue_handler/src/analyze_issue.py	Removes tool entrypoint/orchestration script.
tools/issue_handler/src/init.py	Removes Python package marker for deleted tool.
tools/issue_handler/setup_env.sh	Removes deleted tool’s environment setup helper.
tools/issue_handler/run_tests.sh	Removes deleted tool’s test runner script.
tools/issue_handler/requirements.txt	Removes deleted tool’s Python dependency list.
tools/issue_handler/pytest.ini	Removes deleted tool’s pytest configuration.
tools/issue_handler/integration_tests/test_real_issue.py	Removes deleted tool’s integration test script.
tools/issue_handler/integration_tests/test_analysis.py	Removes deleted tool’s integration test script.
tools/issue_handler/README.md	Removes deleted tool documentation.
tools/issue_handler/.gitignore	Removes deleted tool’s gitignore entries.

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