Bug 41135: disable allowing ofsccreen buffer access for specific domains

Fixes #41135 (closed)

disable the new settings introduced in https://bugzilla.mozilla.org/show_bug.cgi?id=1749323 so that we don't allow certain domains access to offscreen buffers.

Overrides defaults in StaticPrefList.yaml of

# Enable OffscreenCanvas based on the domain allowlist.
- name: gfx.offscreencanvas.domain-enabled
  type: RelaxedAtomicBool
  value: true
  mirror: always

# Domains included in the allowlist.
- name: gfx.offscreencanvas.domain-allowlist
  type: String
  value: "*.zoom.us,zoom.us"
  mirror: never

which are unsafe