Posthumous issue for #97627 and further tracking.

Isidor mentioned previously that there was filtering for keys beginning
with an underscore, but this was only applied to some data in error
responses, not general telemetry events. An alternative approach to this
is filtering exceptions based on the environment on the extension side,
but I figured it would be better to have VS Code do that so that we
don't end up with N many possibly deviant sets of environment detection
logic.

Some external debug adapters use the vscode-extension-telemetry npm package, in which SteVen already implemented appropriate filtering logic. We just need to ensure that (if the linked PR is the approach to take) all debug adapters that send telemetry events prefix their exception properties with ! so that they can be filtered appropriately.