Disable sr list stats

[spco]

Changes

• Disable the stats counting in the right-hand columns of the ScanReport list page. These were causing problems, and taking 45s+ to return results, destabilising the whole platform. For now, these just return "Disabled" text instead. The functionality was always a convenience function, and would be better implemented with regularly scheduled recalculation rather than on-the-fly computation.
• Rework the filter for the SR list API call. This is a little easier to read and (potentially) more stream-lined.

Migrations

NA

Screenshots

Checks

Important: please complete these before merging.

• [x] Run migrations, if any.
• [ ] Update changelog.md, including migration instructions if any.
• [ ] Run unit tests.

[spco]

Before on dev system:

After:

Counting stats is clearly fixed. Performance of the list query seems unaffected.