feat: remove SALESFORCE_SITES SourceType - PSTL-98

[toofff]

PSTL-98

This pull request makes a small change to the SourceType enum in src/resources/Enums.ts by removing the deprecated SALESFORCE_SITES entry. This helps keep the codebase clean and up to date with supported source types.

@GermainBergeron This is the last SourceType to be removed this year.

Acceptance Criteria

• My changes are publicly available, documented, and deployed in production. (i.e. on Swagger)
• JSDoc annotates each property added in the exported interfaces
• The proposed changes are covered by unit tests
• Commits containing breaking changes a properly identified as such
• README.md is adjusted to reflect the proposed changes (if relevant)
• My merge commit message will follow the commit guidelines (See Commit Guidelines)