fix(e2e): strengthen concatenation protocol parameters

[jpraynaud]

Content

This PR includes a strengthening of the Concatenation protocol parameters used by the e2e tests to remove a lottery-induced flakiness in the CI.

• Fix the root cause of the Timeout exhausted waiting for Certificate failures: with k=70, m=105, phi_f=0.77, the two signers together cover fewer than k lottery indexes in ~1 draw out of 177, and when this happens on the first open message of an epoch the aggregator ends the epoch without any certificate and blocks with an unrecoverable epoch gap.
• Scale the initial parameter set from k=70, m=105, phi_f=0.77 to k=274, m=420, phi_f=0.77.
• Scale the updated parameter set (applied at the protocol parameters change phase) from k=83, m=130, phi_f=0.75 to k=283, m=433, phi_f=0.77.
• Both sets keep the all-signers-required property (no single signer can reach the quorum alone).

Benchmark on CI

Scenario	Attempt 1	Attempt 2	Successes	Failures	Success rate
Full (120 std + 7 special modes)	127/127	127/127	254	0	100%
Minimal (120 std)	120/120	120/120	240	0	100%
Total	247/247	247/247	494	0	100%

Pre-submit checklist

• Branch
  • Crates versions are updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested

Issue(s)

Relates to #3452

[github-actions]

Test Results

     5 files  ±0     209 suites  ±0   59m 11s ⏱️ + 6m 45s
 3 374 tests ±0   3 374 ✅ ±0  0 💤 ±0  0 ❌ ±0 
11 228 runs  ±0  11 228 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 54443f9. ± Comparison against base commit 64a7549.

♻️ This comment has been updated with latest results.

[Copilot]

Pull request overview

This PR updates the Concatenation protocol parameters used by the mithril-end-to-end test harness to eliminate lottery-induced CI flakiness that can create an unrecoverable epoch gap (per issue #3452).

Changes:

• Increased the initial Concatenation protocol parameters used when starting the aggregator (k=274, m=420, phi_f=0.77).
• Increased the Concatenation protocol parameters applied during the protocol-parameters-change phase (k=283, m=433, phi_f=0.77).
• Bumped mithril-end-to-end crate version to 0.5.12 (and updated Cargo.lock accordingly).

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
mithril-test-lab/mithril-end-to-end/src/toolkit/exec.rs	Scales the Concatenation protocol parameters applied during the runtime update phase.
mithril-test-lab/mithril-end-to-end/src/mithril/infrastructure.rs	Scales the initial Concatenation protocol parameters used when bootstrapping the aggregator in e2e infrastructure.
mithril-test-lab/mithril-end-to-end/Cargo.toml	Bumps the mithril-end-to-end crate version to reflect the parameter update.
Cargo.lock	Updates lockfile to align with the crate version bump.

[turmelclem]

LGTM 👍