transformer: needs to inject babelHelpers to run exec tests

[Dunqing]

Some plugins will transform code and wrap in helper functions, but now we haven't injected the babelHelpers global variable, which caused our exec tests to fail as long as we use the helper function. e.g: #6573

The implementation is like #6818 and would be better if we could reuse it

[Boshen]

• feat(transform_conformance): add babel runtime to exec tests #7114
• feat(transform_conformance): use node instead of bun for exec tests #7121