Ignore missing deps of module sdk during soong analysis

The module sdk dep might not exist in the branch. This CL moves the
error out of soong analysis phase and into the ninja execution phase.

Test: will use go/abtd
Bug: 380331248
Change-Id: I63d0db2d63a969b4cd43064eb4f5169f07cfd600
diff --git a/sdk/update.go b/sdk/update.go
index 7f4f80a..5a899a2 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -1201,7 +1201,7 @@
 // the snapshot.
 func (s *snapshotBuilder) snapshotSdkMemberName(name string, required bool) string {
 	if _, ok := s.allMembersByName[name]; !ok {
-		if required {
+		if required && !s.ctx.Config().AllowMissingDependencies() {
 			s.ctx.ModuleErrorf("Required member reference %s is not a member of the sdk", name)
 		}
 		return name