chore: Rename StakingPool Mocks

[MilGard91]

Context

Issue: #1103

Changes proposed in this pull request

Rename the StakingPool Mock contracts

Test plan

Please describe the tests cases that you ran to verify your changes. Add further instructions on
how to run them if needed (i.e. migration / deployment scripts, env vars, etc).

Checklist

• Rebased the base branch
• Attached corresponding Github issue
• Prefixed the name with the type of change (i.e. feat, chore, test)
• Performed a self-review of my own code
• Followed the style guidelines of this project
• Made corresponding changes to the documentation
• Didn't generate new warnings
• Didn't generate failures on existing tests
• Added tests that prove my fix is effective or that my feature works

Review

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• 🔨 = I believe this should be changed.
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• 🚀 = Feedback