fix(storage-resize-images): the "Off" content-filter selection stores "False" and fails every event

[cabljac]

The select option "Off (No filtering)" in kits/storage-resize-images/src/config.ts:233 maps to the value "False", not "OFF". A user who picks Off deploys with CONTENT_FILTER_LEVEL=False, and convertHarmBlockThreshold("False") throws Invalid HarmBlockThreshold: False on every event, so the kit is unusable with filtering off. The dead const CONTENT_FILTER_OPTIONS at config.ts:44 shows the intended values and is used nowhere.

Fix: change the select value to "OFF"; use or delete CONTENT_FILTER_OPTIONS. Found during the adversarial review of #3044 (the bug predates it). Part of the #2974 stabilisation work.