pkgman: Suppress the erroneous "aborted: No Error" messages on no internet.

Here's what happens:
 * BPackageManager created a BRefreshRepositoryRequest with a BContext
   of an empty DecisionProvider and itself.
 * Since there is no internet access, the FetchFileJobs that the refresh
   class queued fail. Specifically, the first one does, but then as the
   subsequent ones depend on it, they are all aborted.
 * As some jobs were aborted, the StateListener is notified.
 * The state listener of course has the BPackageManager class as one of
   the listeners, and so calls it, because even though the handler methods
   of BRefreshRepositoryRequest, they are powerless to stop event propagation.
 * The BPackageManager's highest subclass' implementation gets called, which is
   of course pkgman's.
 * pkgman decides to DIE() upon receiving word that a job was aborted.

There are thus four potential solutions to this issue:
 * Rewrite the package kit's event & job handling systems to not be so
   screwed up in terms of propagation. Seriously, there is way too much
   stuff that we send to the "user" in here, and as you can see, it can
   get *extremely* convoluted even for supposedly "simple" tasks. This
   is probably the best "long-term" solution; but obviously is far too
   involved for the present.
 * Only partially rework event handling; specifically in the SupportKit to
   allow JobStateListeners to stop further propagation. This is probably
   the best "medium-term" solution.
 * Do not pass the package manager as the JobStateListener to the
   RefreshRepositoryRequest. This would have the downside that the
   regular notifications about download state, etc. would not be returned
   at all, which we don't want. We could make a shim ... but that would be
   a lot of code for little benefit. The prior solution makes more sense.
 * Completely ignore "JobAborted" notices in pkgman. In fact, this is the
   solution that virtually all other consumers of this API take (although
   some of them seem to have TODOs about it), including package_daemon,
   HaikuDepot, etc., and so it's the one I've taken here. If a "job aborted"
   error is actually fatal, then it's the Package Kit's problem.

Fixes #13075.

src/bin/pkgman/PackageManager.cpp

@@ -69,13 +69,6 @@ PackageManager::JobFailed(BSupportKit::BJob* job)
 }
 
 
-void
-PackageManager::JobAborted(BSupportKit::BJob* job)
-{
-	DIE(job->Result(), "aborted");
-}
-
-
 void
 PackageManager::HandleProblems()
 {

src/bin/pkgman/PackageManager.h

@@ -32,7 +32,6 @@ public:
 			void				SetInteractive(bool interactive);
 
 	virtual	void				JobFailed(BSupportKit::BJob* job);
-	virtual	void				JobAborted(BSupportKit::BJob* job);
 
 private:
 	// UserInteractionHandler