Fix bulk risk acceptance for active findings

[valentijnscholten]

Summary

Fixes #14281

This PR fixes a bug where active findings could not be risk accepted via the bulk edit menu, even though individual risk acceptance worked fine and simple risk acceptance was enabled on the product. This now matches the Pro UI.

Changes

• Remove invalid restriction: Removed the check that prevented active findings from being risk accepted in bulk operations
• Update tests: Modified test_bulk_edit_active_finding_can_accept_risk to verify that active findings can now be risk accepted successfully in bulk
• Update test: Modified test_bulk_edit_shows_multiple_warning_messages to verify no warning appears when risk accepting active findings
• Remove obsolete code: Removed the warning message about "active findings cannot be risk accepted"
• Simplify return value: Updated _bulk_update_risk_acceptance helper function to return only the count of skipped findings

Root Cause

The bulk update function incorrectly checked if finding.active: and skipped risk acceptance for active findings, showing a warning message. However:

1. The individual risk acceptance endpoint (simple_risk_accept view) has NO such restriction
2. The simple_risk_accept helper function automatically sets finding.active = False when accepting risk
3. DefectDojo Pro allows bulk risk acceptance of active findings

This was an inconsistency between bulk and individual operations that had no technical justification.

Behavior Change

Before: Bulk risk acceptance of active findings failed with error message "Active findings cannot be risk accepted"

After: Bulk risk acceptance of active findings works correctly, matching individual behavior. The finding becomes inactive (risk_accepted=True, active=False) after risk acceptance.

[mtesauro]

Approved