fix(build, docker, dockerfile): fix panic expected stage "dockerfile" content digest label to be set!

Disable provenance to avoid creating an index manifest (result of Buildx build), which is not handled correctly with the current code.

```
panic: expected stage "dockerfile" content digest label to be set!

goroutine 1 [running]:
github.com/werf/werf/v2/pkg/build.(*BuildPhase).calculateStage(0x14000cf0a00, {0x104100598, 0x14000b12090}, 0x14000371680, {0x10412ad20, 0x1400095f800})
	/git/pkg/build/build_phase.go:985 +0xb68
github.com/werf/werf/v2/pkg/build.(*BuildPhase).onImageStage(0x14000cf0a00, {0x104100598, 0x14000b12090}, 0x14000371680, {0x10412ad20, 0x1400095f800})
	/git/pkg/build/build_phase.go:744 +0xf8
```

Signed-off-by: Aleksei Igrychev <aleksei.igrychev@palark.com>

Author: alexey-igrychev

pkg/docker/image.go

@@ -209,6 +209,9 @@ func CliBuild_LiveOutputWithCustomIn(ctx context.Context, rc io.ReadCloser, args
 
 	if useBuildx {
 		buildOpts.EnableBuildx = true
+
+		// TODO: --provenance=false is a workaround for index manifests that we cannot handle properly with current code base (fix in v3).
+		args = append([]string{"--provenance=false"}, args...)
 	} else {
 		var err error
 		args, err = checkForUnsupportedOptions(ctx, args...)