ci: Remove redundant assemble step from pre-merge workflow (#1267)

The Debug and Release variants are already built via ./gradlew assemble
in the Build workflow (build.yml), making this step redundant.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: runningcode

.github/workflows/pre-merge.yaml

@@ -45,6 +45,3 @@ jobs:
           name: test-results-${{ matrix.os }}
           path: plugin-build/build/reports/tests/
         if: always()
-
-      - name: Build the Debug and Release variants
-        run: ./gradlew assemble