azure-monitor-opentelemetry-exporter needs typing updates for mypy version 1.19.1

[azure-sdk]

ACTION NEEDED: This version of mypy will be merged on 2026-04-13. The build will begin to fail for this library if errors are not fixed.

Library name: azure-monitor-opentelemetry-exporter
Mypy version: 1.19.1
Mypy Build: Link to build (2026-01-25)
How to fix: Run the next-mypy tox command at the library package-level and resolve the typing errors.

1. ../azure-monitor-opentelemetry-exporter>pip install "tox<5"
2. ../azure-monitor-opentelemetry-exporter>tox run -e next-mypy -c ../../../eng/tox/tox.ini --root .

See the Typing Guide for more information.