Slashing penalty not adequately specified in ChainParams

[conorsch]

Describe the bug
Recent changes to ChainParams appear to have broken pd testnet join on preview.

To Reproduce
Steps to reproduce the behavior:

1. pd testnet unsafe-reset-all
2. pd testnet join testnet-preview.penumbra.zone
3. Observe error:

pd testnet join testnet-preview.penumbra.zone
2022-12-12T17:27:07.454822Z  INFO fetching genesis
Error: slashing_penalty_downtime_bps must be set in ChainParameters

Expected behavior
Can join testnet-preview fine and interact with preview network.

Screenshots
N/A

Additional context
Looks related to #1721 ; some follow-up may be necessary.

[conorsch]

Looks like preview was misconfigured to run the prior testnet tag; hat-tip to @erwanor for catching it. Pushed up a fix-it commit here: 17a3267 monitoring deploy and will test again shortly.

[conorsch]

That fixed it! I'm now able to join testnet-preview, because it's actually running the "main"-tagged container, as intended.