This is a very minor UX change. The current "No Alert rules" present
table row has the `alert_header` class attached. This changes the cursor
and some other stuff and makes sense with the populated table but less
sense with the unpopulated table. So removing it the latter case.
There's no corresponding table column for this table header. The
placeholder link for silences was removed in e8800730.
Accordingly, regenerate `web/ui/bindata.go` by running:
make assets format
James Turnbull
Julius Volz
Fabian Reinartz
Erdem Agaoglu
Harmen
Matt Bostock