Drop channel input and REVERTME pin

The channel dispatch input was passed as dev-channel to the shared
workflow. That feature was dropped from images-shared#480 (Workbench
preview branch override is handled separately via
BAKERY_WORKBENCH_RELEASE_BRANCH). Remove the input and the pass-through
so the manual-dispatch form doesn't advertise an unused knob.

Also drops the REVERTME pin that held the shared workflow at the
abandoned release-stream-filter branch — bakery-build-native.yml on
main (via #480) now accepts image-version and dev-stream, so @main is
the correct ref.

Author: bschwedler

.github/workflows/development.yml

@@ -10,10 +10,6 @@ on:
         description: "Dev stream to build (e.g. 'daily')"
         required: false
         type: string
-      channel:
-        description: "Upstream channel reference (e.g. branch codename)"
-        required: false
-        type: string
 
   schedule:
     # Hourly rebuild of dev images
@@ -74,7 +70,6 @@ jobs:
       matrix-versions: "exclude"
       image-version: ${{ inputs.version }}
       dev-stream: ${{ inputs.stream }}
-      dev-channel: ${{ inputs.channel }}
       # Push on merges to main, scheduled rebuilds, and dispatches targeting main.
       push: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' || github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' && github.ref == 'refs/heads/main' }}