[docs] Fix documentation inconsistencies with current tooling

[Copilot]

Several doc files contained stale references to setup.py/setup.cfg (superseded by pyproject.toml) and outdated pinned versions for mypy and pyright.

Changes

doc/dev/static_type_checking.md

• mypy pin: 1.9.0 → 1.19.1
• pyright pin: 1.1.287 → 1.1.407 (3 occurrences)
• Broken link azure-eventhub/setup.py#L73 → azure-eventhub/pyproject.toml#L27
• py.typed registration: replaced include_package_data + package_data in setup.py with [tool.setuptools.package-data] in pyproject.toml

doc/dev/tests.md

• Removed setup.py and setup.cfg from required SDK root file list; added pyproject.toml

doc/dev/dataplane_generation.md

• "like setup.py, README.md" → "like pyproject.toml, README.md"

doc/dev/packaging.md

• Added top-of-file callout clarifying this doc describes legacy setup.py-based packaging; links to current sdk/template/azure-template

doc/dev/changelog_updates.md

• Removed "(instead of or alongside setup.py)" — packages use pyproject.toml exclusively

doc/deprecation_process.md

• Updated metadata file list to cite pyproject.toml classifiers instead of setup.py
• Merged the duplicate ## setup.py → Development Status classifier step into the existing ## pyproject.toml section

doc/eng_sys_checks.md

• Dropped "right next to each package's setup.py" from the pyproject.toml section intro
• 5 occurrences of setup.py (or setup.py/pyproject.toml) updated to reference pyproject.toml only

doc/tool_usage_guide.md

• verifysdist description: setup.py → pyproject.toml

All version numbers verified against eng/tools/azure-sdk-tools/azpysdk/mypy.py and pyright.py; package structure claims verified against sdk/template/azure-template/.