HA state disappears on Kea app page

This is a result of the Stork 0.13.0 sanity checks: #441 (comment 174642)

@godfryd pointed out that "HA state disappears on Kea app page". Repro:

• add in the demo two kea instances (ha1 and ha2)
• open kea apps page
• open both apps on separate tabs
• stop ha1/dhcp4 service in Stork Env Simulator
• on ha1 tab there should be presented info about connectivity issues
• on ha2 tab HA state may be presented by when tabs are switched between ha1 and ha2 then HA state disappears on ha2 tab (it may reappear after a while when new HA state is retrieved from the server)