Don't factor in chains that are down for dex-agg swaps

[fl-y]

Describe the bug
Despite Osmosis chain being down, the dex-agg acted as if the dex was available.
Not an issue atm since we only have one dex integrated and the tx will fail anyway with the right error message.
However, will be an issue when we have multiple dexes integrated and the dex-agg recommends unavailable swaps.

To Reproduce
(Applicable since Osmosis is down at the time of writing)
Input corresponding values to the swap widget and see osmosis swaps being used.

Expected behavior

• Swap widget not displaying swaps if Osmosis is down & Osmosis is the only dex.
• Swap widget not using dexes that are down when there are multiple

Additional context
Slack thread