Errors only disapear if resolved due to e.g. successfull API call

[pkuehnel]

Many errors (e.g. get vehicle info) occur and the issue persists until a vehicle info call succeeds. In many circumstances, this will never happen, so the issue never disappears. There should be a max age of the last occurrence after which the issue is handled as resolved. Another way would be to specify conditions when issues are resolved (e.g. get vehicle info resolves if Fleet Telemetry is connected).