Context:
Since we have introduced the KPI/process overview logic, we have no need for process goals anymore. We can delete the index as well as any related DTOs. Note that this was already partially attempted in OPT-6175, but some details have been overlooked. The migration IT introduced also does not correctly assert the deletion of the goals index.

AT:

• ProcessGoalIndex class is deleted
• Migration deletes processgoalsIndex
• MigrationIT asserts this deletion (ensure correct indexName in indexExists request)
• Any related process goals DTOs are removed
• Ensure no further process goals logic/code persists in the codebase

Testing Notes:

• After upgrade to 3.9.0, the process goals index no longer exists in ES