Lessen test lab flakyness

[Alenar]

• Update devnet parameters for faster epoch & immutable files creation
• Set the epoch offset (for signer & stake distribution) from 0 to 1 Postponed until we find why signers must wait until epoch 3 to sign
• Adjust aggregator & signers run interval to be faster.
• Add a new step in the E2E tests to wait until the current epoch is at least equal to the epoch offset (below it the signers won't be able to sign).
• Set the number of signers & cardano pool node to 2 since the aggregator register signatures faster since Use single signature store in Mithril Aggregator #295.
• Quick fix
  • aggregator: multi-signer won't crash if the current epoch is lower than the epoch offset
  • signer: init protocol initializer earlier to have them even if following code have an error.

[github-actions]

Unit Test Results

229 tests  ±0   229 ✔️ ±0   6m 14s ⏱️ -50s
  18 suites ±0       0 💤 ±0 
    6 files   ±0       0 ❌ ±0 

Results for commit e1e5125. ± Comparison against base commit 8dab45f.

♻️ This comment has been updated with latest results.

[jpraynaud]

LGTM 🥳