fix(plugin-workflow): fix loop variable

[mytharcher]

Description (Bug 描述)

Variable for loop item should be same as loop target item.

Steps to reproduce (复现步骤)

1. Add loop node.
2. Add any node which could use variable to the loop.
3. Select scope variable in added node.

Expected behavior (预期行为)

"Loop item" should be same level as loop target.

Actual behavior (实际行为)

One more level as node id in the variable options.

Related issues (相关 issue)

#2157.

Reason (原因)

Node variable has been refactored, loop variables missed.

Solution (解决方案)

Also refactor loop node on scope variable options.

[height]

This pull request has been linked to 1 task:

• T-874 动态表达式数据源选择查询多条数据时，变量路径错误 (unlink task)

💡Tip: Add "Close T-874" to the pull request title or description, to a commit message, or in a comment to mark this task as "Done" when the pull request is merged.