Windows tests setting an unused `WITH_OTPROTCOL` CMake option

[dbarker]

The *.otprotocol.* windows CI tests set an WITH_OTPROTCOL CMake option that is not used. The tests may not be covering what they intend to.

Tests from ci/do_ci.ps1 setting the option include:

• cmake.exporter.otprotocol.test
• cmake.exporter.otprotocol.with_async_export.test
• cmake.exporter.otprotocol.dll.test

CMake warns about the unused option. https://github.com/open-telemetry/opentelemetry-cpp/actions/runs/15336632592/job/43155086475#step:7:212

  Manually-specified variables were not used by the project:

    WITH_OTPROTCOL