fix: Interpret x/0 collateral liquidity as 100%

[toteki]

Description

Quick bugfix to solve an issue we found in QA

Collateral liquidity was being interpteted as zero before any collateral was added (even with nonzero liquidity)

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Author Checklist

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I have...

• included the correct type prefix in the PR title
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• added a changelog entry to CHANGELOG.md
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• confirmed the correct type prefix in the PR title
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[codecov-commenter]

Codecov Report

Merging #1357 (87fb8e2) into main (5cbf948) will increase coverage by 0.18%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1357      +/-   ##
==========================================
+ Coverage   52.22%   52.41%   +0.18%     
==========================================
  Files          69       69              
  Lines        6836     6863      +27     
==========================================
+ Hits         3570     3597      +27     
  Misses       2988     2988              
  Partials      278      278              

Impacted Files	Coverage Δ
x/leverage/client/tests/suite.go	95.65% <100.00%> (ø)
x/leverage/client/tests/tests.go	100.00% <100.00%> (ø)
x/leverage/keeper/collateral.go	69.85% <100.00%> (+0.68%)	⬆️

[robert-zaremba]

Pre-approving. let's add more details to the comment.