mgr/dashboard: Fix regression on table error handling

mgr/dashboard: Fix regression on table error handling

The regression was introduced by #35290 through the use of the new tab module
the pools and host listing got wrapped into the new usage, however they needed
to use the table as Viewchild and the table was static before, but it's now
dynamic. This resulted in an empty variable that wasn't filled with the
right table object. The calling of the ".reset()" was not possible
during an error case and produced an error in console trying to access
"reset" of undefined, by not calling "reset" the table get's stuck with an
rotating reload symbol.

Fixes: https://tracker.ceph.com/issues/46660
Signed-off-by: Stephan Müller <smueller@suse.com>