Backport PR #5788: run cells with `silent=True` in `%run nb.ipynb`

- more consistent with running scripts
- avoids a bunch of uncapturable `Out[n]: ` outputs when running a notebook.

closes  #5685

IPython/core/interactiveshell.py

@@ -2601,7 +2601,7 b' class InteractiveShell(SingletonConfigurable):'
                     # raised in user code.  It would be nice if there were
                     # versions of run_cell that did raise, so
                     # we could catch the errors.
-                    self.run_cell(cell, store_history=False, shell_futures=False)
+                    self.run_cell(cell, silent=True, shell_futures=False)
             except:
                 self.showtraceback()
                 warn('Unknown failure executing file: <%s>' % fname)