fix(u2c): make v1 handle negative host priorities

[robstax]

This pull request addresses

u2c service will start returning -1 host priority values indicating that the host should not be used. the current services implementation does not correctly handle negative values.

by making the following changes

This is a bug fix, not a breaking change. The core logic is preserved:

homeCluster filtering - Still filters by host.homeCluster when no clusterId is provided
clusterId filtering - Still filters by host.id === clusterId when provided
Priority selection - Still selects the host with the lowest priority number (priority 1 > priority 5)
Failed host handling - Still resets failed flags when all hosts have failed
What the fix actually does
The only behavioral difference is for hosts with priority <= 0:

Before: A host with priority: -1 could "win" the reduce because -1 > undefined is false, and the comparison logic was flawed with the empty object {} initial value
After: Hosts with priority <= 0 are excluded upfront, and if no valid hosts remain, it falls back to defaultUrl

Change Type

• 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 change)
• Documentation update
• Tooling change
• Internal code refactor

The following scenarios were tested

< ENUMERATE TESTS PERFORMED, WHETHER MANUAL OR AUTOMATED >

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• This PR is related to
  • Feature
  • Defect fix
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I certified that

• I have read and followed contributing guidelines
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• All existing and new tests passed
• I have updated the documentation accordingly

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