Fix production builds always enabling Go coverage instrumentation

Fixup: f2e901f
Signed-off-by: Michael Fritch <mfritch@suse.com>

Author: mgfritch

.github/workflows/build-k3s.yaml

@@ -95,7 +95,7 @@ jobs:
           TREE_STATE=${{ steps.git_vars.outputs.tree_state }}
           COMMIT=${{ steps.git_vars.outputs.commit }}
           DIRTY=${{ steps.git_vars.outputs.dirty }}
-          GOCOVER=${{ inputs.test-coverage && '1' || '0' }}
+          GOCOVER=${{ inputs.test-coverage && '1' || '' }}
         push: false
         provenance: mode=min
         platforms: ${{ steps.platforms.outputs.platforms }}