ci: force regeneration of testdata.json for testimage

The test phase was failing with:
  ERROR: File .../core-image-minimal-*.rootfs.testdata.json not found

This happens because testdata.json is generated during image build,
but the test phase modifies IMAGE_INSTALL after the build phase.

Solution: Force regeneration of testdata_json task before running testimage.
This ensures the JSON reflects the actual packages in the test image.

Author: rpcme

.github/workflows/build-test-recipe.yml

@@ -290,8 +290,9 @@ jobs:
              export SSTATE_DIR=/sstate-cache
              export DL_DIR=/downloads
              export BB_ENV_PASSTHROUGH_ADDITIONS="$BB_ENV_PASSTHROUGH_ADDITIONS SSTATE_DIR DL_DIR"
+             bitbake core-image-minimal -c testdata_json -f
              bitbake core-image-minimal
-             bitbake core-image-minimal -f -c testimage
+             bitbake core-image-minimal -c testimage
              resulttool report tmp/log/oeqa/testresults.json | tee -a ${{ matrix.machine }}-resulttool_report.txt'
             set -e
             echo RECIPES to test: $RECIPES