[BUG] Signing requires all authorities to be online

[1xstj]

Describe the bug
Consider a DKG network with t=3 and n=5. Ideally if one of the nodes crashes/does not respond, the signing should progress since we still have t+1 (4) authorities online and signing.

To Reproduce
Steps to reproduce the behavior:

1. Start a local network with 3-of-5 authorities
2. Wait until the genesis keygen is completed and atleast one proposal is signed
3. Kill one of the authority nodes, the network should have 4-of-5 authorities now
4. Block production continues, but any proposals send to the DKG are not signed.

Expected behaviour
Proposals are signed as long as t+1 authorities are online.