revert: Make Wait node fully durable by removing in-memory execution path (backport to release-candidate/2.16.x)

[n8n-assistant]

Description

Backport of #28538 to release-candidate/2.16.x.

Checklist for the author (@shortstacked) to go through.

• Review the backport changes
• Fix possible conflicts
• Merge to target branch

After this PR has been merged, it will be picked up in the next patch release for release track.

Original description

Summary

Reverts #27066 (f025a786e75ec962fcaca469c107324eea8548a3).

This restores the original Wait node behavior where waits shorter than 65 seconds run in-memory via setTimeout, and removes the DB-server-clock-anchored scheduling infrastructure introduced in the reverted PR.

What is restored:

• Wait node: the < 65s in-memory execution path
• WaitTracker: 60s poll interval with Date.now()-based timing
• ExecutionRepository: original getWaitingExecutions() without lookahead window

What is removed:

• ClockRepository and DbClockService (DB server clock syncing)
• n8n_db_clock_skew_ms Prometheus gauge
• 5s poll interval and 15s lookahead window

Review / Merge checklist

• I have seen this code, I have run this code, and I take responsibility for this code.
• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with Backport to Beta, Backport to Stable, or Backport to v1 (if the PR is an urgent fix that needs to be backported)

[codecov]

Bundle Report

Changes will increase total bundle size by 9.28kB (0.02%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
editor-ui-esm	45.38MB	9.28kB (0.02%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: editor-ui-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
assets/worker-*.js	4.65kB	3.17MB	0.15%
assets/useRootStore-*.js	4.63kB	131.2kB	3.66%

[codecov]

Codecov Report

❌ Patch coverage is 70.90909% with 16 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
packages/cli/src/wait-tracker.ts	76.19%	10 Missing ⚠️
...s/@n8n/db/src/repositories/execution.repository.ts	0.00%	6 Missing ⚠️

📢 Thoughts on this report? Let us know!