fix: fix slow proxy test

[camfairchild]

Description

One of the calls ran during a proxy-pallet test had a long run time (>60s) due to the work hash search.
This PR lowers the difficulty of the test environment to make the runtime much shorter (<0.05s).

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Other (please describe): Test fix

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have run cargo fmt and cargo clippy to ensure my code is formatted and linted correctly
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

Screenshots (if applicable)

Please include any relevant screenshots or GIFs that demonstrate the changes made.
Before:

After:

[open-junius]

Thank you! there is difficult computing in the register network call. It can help to reduce the execution time