release_3185

All PRs included

#2468 Stop A/B/C test on 'Start now' buttons
#2452 Refactor Benefit cap calculator (Making benefit rates and type configurable)
#2462 Consolidated content changes for opposite and same sex (Sweden)
#2457 Add test to ensure all flows are visualisable
#2454 Restore indexable_content behaviour for outcome nodes (rebased)
#2435 Add note to docs to commit changes before updating checksum
#2400 Avoid double render error if exception raised after render
#2408 Introduce on_response blocks to set attributes on calculator

PRs to check post-deployment

#2468 Stop A/B/C test on 'Start now' buttons
#2452 Refactor Benefit cap calculator (Making benefit rates and type configurable)
#2462 Consolidated content changes for opposite and same sex (Sweden)