Fix StopInfoBreakpoint::ShouldNotify when a callback deletes the site we hit.

When we hit a breakpoint site all of whose owners are internal, we don't
broadcast that event to the public event queue.  However, we were checking
whether that was true in the ShouldNotify method, which gets run after the
breakpoint callbacks get run.  If the breakpoint callback deletes the site
we just hit, we no longer have the information to make that determination.

This patch just gathers the "was all internal" fact when the StopInfoBreakpoint
gets made, which happens before anyone has a chance to delete the site, and then
uses that cached value.

This bug was causing a couple of tests (including TestStopAtEntry.py) to fail
when using new the macOS Ventura dyld support.

Differential Revision: https://reviews.llvm.org/D127997