layerStore: clean residual resources in layerStore when remove an image

# - type: feat, fix, docs, style, refactor, test, chore
 # - scope: can be empty (eg. if the change is a global or difficult to assign to a single component)
 # - subject: start with verb (such as 'change'), 50-character line

 body: 72-character wrapped. This should answer:
 # * Why was this change necessary?
 # * How does it address the problem?
 # * Are there any side effects?

 footer:
 # - Include a link to the ticket, if any.
 # - BREAKING CHANGE

Signed-off-by: zvier <zvier20@gmail.com>

layers.go

@@ -1013,6 +1013,7 @@ func (r *layerStore) deleteInternal(id string) error {
 		if layer.MountPoint != "" {
 			delete(r.bymount, layer.MountPoint)
 		}
+		r.deleteInDigestMap(id)
 		toDeleteIndex := -1
 		for i, candidate := range r.layers {
 			if candidate.ID == id {
@@ -1044,6 +1045,27 @@ func (r *layerStore) deleteInternal(id string) error {
 	return err
 }
 
+func (r *layerStore) deleteInDigestMap(id string) {
+	for digest, layers := range r.bycompressedsum {
+		for i, layerID := range layers {
+			if layerID == id {
+				layers = append(layers[:i], layers[i+1:]...)
+				r.bycompressedsum[digest] = layers
+				break
+			}
+		}
+	}
+	for digest, layers := range r.byuncompressedsum {
+		for i, layerID := range layers {
+			if layerID == id {
+				layers = append(layers[:i], layers[i+1:]...)
+				r.byuncompressedsum[digest] = layers
+				break
+			}
+		}
+	}
+}
+
 func (r *layerStore) Delete(id string) error {
 	layer, ok := r.lookup(id)
 	if !ok {