Previously, we only did this when IsCallerExternalProcess() returned false.
There are three reasons for changing this:
1. There seem to be cases where IsCallerExternalProcess() returns true even when marshaling for a COM query in the MTA.
2. After bug 1627084, we pre-build a11y handler payloads on the main thread for bulk fetch calls. That will marshal interceptors. However, IsCallerExternalProcess() can't work in that case because it's not running on the thread on which the COM call is being handled.
3. If MSHLFLAGS_NOPING is used, Release calls from remote clients are never sent to the server. So, as soon as we use NOPING for our parent process, we're already going to leak references, even if we don't use NOPING for external callers. Put another way, as soon as we use NOPING for one caller, we may as well use it for all callers because COM pinging will never release the object anyway.
Differential Revision: https://phabricator.services.mozilla.com/D84778