fix: oas2 collectionFormat when not 'multi'

[tim-lai]

Description

Fix OAS2 collectionFormat handling for non-multipart cases

collectionFormat: csv
collectionFormat: tsv
collectionFormat: ssv
collectionFormat: pipes

Motivation and Context

Previous OAS2 multipart fixes did not cover non-multi cases.

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• No code changes (changes to documentation, CI, metadata, etc)
• Dependency changes (any modification to dependencies in package.json)
• 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)

Checklist:

• 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.