fix: Ensure consistent rollback logic for failed SQL operations

[john-bodley]

SUMMARY

This PR ensures we consistently handle rollbacks when an error occurs. Throughout the code there's inconsistent logic of the form:

try:    
    if commit:
        db.session.commit()
except SQLAlchemyError as ex:
    db.session.rollback()

as well as:

try:    
    if commit:
        db.session.commit()
except SQLAlchemyError as ex:
    if commit:
        db.session.rollback()

This PR—by way of git grep -B 1 rollback—removes the unnecessary if commit checkout before a rollback because we want to rollback any operation which failed—pre commit—in the transaction regardless of whether we're planning to commit, i.e., save the state.

Regarding commits per here it's worth noting that once committed a rollback is not viable.

The transaction can not undo changes after COMMIT execution.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

CI.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[zhaoyongjie]

commit and rollback are mutually exclusive. lgtm. BTW, please don't care about the code coverage ci failure, the master branch has fixed it.