Remove mentions of Optimize and Accelerate

[AmanVarshney01]

Summary

• Removed "optimize" and "accelerate" from the EXAMPLES_DIR_ACCEPT list in constants
• Removed the Prisma Optimize and Prisma Accelerate choices from the CLI selection prompt
• Removed Accelerate mention from the Prisma Starter description
• Removed optimize-specific install and subfolder handling logic
• Updated validation error message to no longer reference optimize or accelerate
• Updated tests to reflect the changes

Test plan

• All existing tests pass (22/22)
• Lint and format checks pass