fix(jira): correct Data Sensitivity field ID and replicate Jira's real classification scheme

The auto-create-ticket call was sending customfield_11233 (a field that
doesn't exist in the project) instead of the real Data Sensitivity field
customfield_11814, which made Jira reject the WHOLE issue and silently
block ticket creation for every new test.

Also replaces Aegis's invented 4-tier data_classification scheme
(public_release/general_use/confidential/restricted) with the 6 values
Jira's Data Sensitivity field actually uses (public/general_use/
internal_use_only/trusted_people/customer_content/pii), since that is
the classification the organization actually applies. Includes a data
migration remapping existing rows and a defensive retry if Jira ever
rejects an unscreened custom field again.

backend/app/schemas/test.py

@@ -299,8 +299,8 @@ class TestOut(BaseModel):
     retest_of: uuid.UUID | None = None
     # Assign retest_count = 0
     retest_count: int = 0
-    # Assign data_classification = "confidential"
-    data_classification: str = "confidential"
+    # Assign data_classification = "internal_use_only"
+    data_classification: str = "internal_use_only"
 
     # Technique info (populated when joined)
     technique_mitre_id: str | None = None