ci: add team Slack mention to version bump pipeline notifications

[ninalee12]

Summary

• Add team Slack mention to the blocked-state notification so the team is pinged when the version bump pipeline needs manual approval
• Add team Slack mention to the pass/fail notification so the team is informed of pipeline completion or failure

Context

Version bump pipelines are triggered centrally by the centralized-version-bump pipeline. Previously, only the release engineer who triggered the pipeline was notified — leaving teams unaware when their pipeline was waiting for approval or had finished.

Feel free to suggest a different Slack handle or a dedicated person to ping if this isn't the right one for your team.

Test plan

• Verify Slack notification in the team channel includes the team mention on next version bump run

🤖 Generated with Claude Code

[prodsecmachine]

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