fix solve time for logical dispatch model

[samgdotson]

Summary of changes

This PR adds addresses a bug that caused a major slowdown for the logical dispatch model when using it with the CapacityExpansion problem. I fixed the issue by removing the call for synchronize_units within the base Model class since users can do this manually and CapacityExpansion will do it by default. It should only happen once, but was instead happening for every evaluation.

Types of changes

• 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)
• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

Associated Issues and PRs

• Issue: #

Associated Developers

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[samgdotson]

@SamarAbdelkawy, I'm adding you as a reviewer to this pull request since you might be interested in using Osier at some point!

[katyhuff]

Looks good, reviewed together.