fix(ci): fix flaky yarn install in lint-and-build-ctst job

[delthas]

Summary

The lint-and-build-ctst job intermittently fails during yarn install with a corrupt cache error (example failure):

error https://registry.yarnpkg.com/picomatch/-/picomatch-2.3.1.tgz: Extracting tar content of undefined failed,
the file appears to be corrupt: "ENOENT: no such file or directory, chmod
'/home/runner/.cache/yarn/v6/npm-picomatch-2.3.1-...-integrity/node_modules/picomatch/package.json'"

Root cause

Yarn v1 fetches and extracts packages in parallel by default. This can cause a race condition where concurrent tar extractions corrupt files in the local cache directory. Once a corrupted entry is written, the actions/setup-node cache action persists it to the GitHub Actions cache, causing subsequent workflow runs to restore the bad state and fail deterministically until the cache key rotates.

Solution

Two complementary mitigations:

1. --network-concurrency 1 — serializes package fetching and extraction, preventing the race condition that causes corruption in the first place. This is the primary fix; the slight increase in install time is negligible compared to the cost of flaky CI reruns.

2. || (yarn cache clean && yarn install --network-concurrency 1) — if the cache is already corrupt from a previous run, the first yarn install fails, the fallback wipes the local cache, and the retry succeeds with a clean slate. This handles the transitional period until all runners pick up a fresh cache.

Fixes ZENKO-5246

[bert-e]

Hello delthas,

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[bert-e]

Waiting for approval

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• the author

• 2 peers

[francoisferrand]

Looking at yarn tickets, it seems this may not be the root cause: c.f. yarnpkg/yarn#7212 (comment) for exemple
→ there may be some issues in our dependency tree instead, we should probably look there (as well and/or in addition)...

[delthas]

/approve

[bert-e]

I have successfully merged the changeset of this pull request
into targetted development branches:

• ✔️ development/2.14

The following branches have NOT changed:

• development/2.10
• development/2.11
• development/2.12
• development/2.13
• development/2.5
• development/2.6
• development/2.7
• development/2.8
• development/2.9

Please check the status of the associated issue ZENKO-5246.

Goodbye delthas.

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