Build external repos with keystore

[dhaidashenko]

• Move get ref from pr to .github repo to be shared with other repos.
• Add keystore bump to the chainlink build to catch breaking changes

[Copilot]

Pull request overview

This PR updates the “Build External Repositories” GitHub Actions workflow to use a shared ref-parsing script hosted in smartcontractkit/.github, and tightens the external build check by also bumping the chainlink-common/keystore module when building Chainlink Core.

Changes:

• Switch build_external.yml to checkout and execute get-refs-from-pr-body.js from smartcontractkit/.github (sparse checkout into dot_github/).
• Add an explicit go get for github.com/smartcontractkit/chainlink-common/keystore@${COMMON_SHA} when building /chainlink.
• Remove the local .github/scripts/get-refs-from-pr-body.js script from this repo (now sourced externally).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
.github/workflows/build_external.yml	Uses shared script from smartcontractkit/.github and bumps chainlink-common/keystore in the Chainlink build step.
.github/scripts/get-refs-from-pr-body.js	Removes the local script implementation (relocated to shared org .github repo).

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[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 2.

Benchmark suite	Current: 64a24c5	Previous: 7d3ddf4	Ratio
BenchmarkKeystore_Sign/nop/in-process	758.2 ns/op	278.9 ns/op	2.72

This comment was automatically generated by workflow using github-action-benchmark.