timers: move big impl comment to /internal/
To be paired with the commits from #26583
Specifically: 1a6fb71f
Checklist
-
make -j4 test(UNIX), orvcbuild test(Windows) passes -
commit message follows commit guidelines
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
To be paired with the commits from #26583
Specifically: 1a6fb71f
make -j4 test (UNIX), or vcbuild test (Windows) passes