Migrate CI Workflows to Tenki Runners

[asutosh23]

About Tenki

Tenki provides high-performance, flexible GitHub Runners that replace self-hosted or legacy CI solutions with a faster, more secure, and cost-efficient alternative.

With Tenki, teams benefit from:

• ⚡ Faster pipelines: ~30% average improvement in job execution time through optimized infrastructure
• 💰 Significant savings: up to ~90% cheaper compared to traditional CI runner solutions
• 🔒 Stronger security: runners run on ephemeral VMs, ensuring clean, isolated environments for every job
• 📈 Scalable options: a broad catalog of runner types with built-in autoscaling to match workload demand

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Performance Comparison

Below are benchmark results comparing Tenki vs. our previous CI solution:

Performance Comparison

Below are benchmark results comparing Tenki vs. our previous CI solution:

Workflow Step	Previous Solution (avg)	Tenki (avg)	Improvement
Build RIT Repo	1m 46s	1m 27s	18% faster
Run Rootstock Integration Tests	1h 29m 56s	1h 23m 29s	7% faster
Total CI Duration	1h 33m 57s	1h 25m 4s	9% faster

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Modifications in This PR

• Updated GitHub Actions workflows to use Tenki runner labels

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✅ This PR completes the initial migration to Tenki runners.