Fix gallery zip scan context (#3433)

* fix zip scan context
* move ValueOnlyContext to utils, use it for zipCtx

pkg/utils/context.go

@@ -0,0 +1,22 @@
+package utils
+
+import (
+	"context"
+	"time"
+)
+
+type ValueOnlyContext struct {
+	context.Context
+}
+
+func (ValueOnlyContext) Deadline() (deadline time.Time, ok bool) {
+	return
+}
+
+func (ValueOnlyContext) Done() <-chan struct{} {
+	return nil
+}
+
+func (ValueOnlyContext) Err() error {
+	return nil
+}