improve logs for retry.Do error scenarios(troubleshoting improvement)

[fernandezlautaro]

Several pieces in of the WR in CRE relies on the retry.Do feature, where when eventually fails the real cause gets swallowed here.

So this fix improves readability when we are troubleshooting logs

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Supports

[github-actions]

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[github-actions]

📊 API Diff Results

No changes detected for module github.com/smartcontractkit/chainlink-common

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[Copilot]

Pull request overview

Improves troubleshooting for pkg/utils/retry.Strategy.Do by ensuring terminal retry failures (context cancellation/timeout or max retries) include the last callback error in the returned error message, and updates tests accordingly.

Changes:

• Track and surface the last callback error in the context done and max retry attempts reached error paths.
• Expand retry tests to assert the returned error contains both the retry wrapper error and the underlying callback error details.
• Add new test cases to validate that the last callback error is surfaced.

Reviewed changes

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

File	Description
pkg/utils/retry/retry.go	Adds lastKnownErr tracking and includes it in terminal error messages for better diagnostics.
pkg/utils/retry/retry_test.go	Updates error assertions to check multiple substrings and adds new cases around “last error” behavior.

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