Only show CSA Before Workshop note for Summer Workshop subject - #51353

This PR refactors how we show the "Before the Workshop" section in workshop enrollment receipt and reminder emails to tailor the information better to the specific workshop case. This change affects both the enrollment receipt and enrollment reminder emails but it does not depend on whether a given email is a receipt or reminder email so I arbitrarily chose the receipt emails to demo below.

Case: CSA summer workshop email (no change expected)

Original:

New:

Case: CSA not summer workshop (e.g. CSA capstone in this case) email

Original:

New:

Case: Not CSA (e.g. CSD in this case) summer workshop email (no change expected)

Original:

New:

Links

Jira ticket: here

Testing story

Local testing.

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked