Fix: The Context Generator(Transformer) node can only be followed by a Tokenizer(Indexer) and a Context Generator(Transformer). #9869 (#10515)

### What problem does this PR solve?

Fix: The Context Generator node can only be followed by a Tokenizer and
a Context Generator. #9869
### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/data-flow/canvas/index.tsx

@@ -292,6 +292,7 @@ function DataFlowCanvas({ drawerVisible, hideDrawer, showLogSheet }: IProps) {
                 clearActiveDropdown();
               }}
               position={dropdownPosition}
+              nodeId={connectionStartRef.current?.nodeId || ''}
             >
               <span></span>
             </NextStepDropdown>