VI variable replacement broken with Aesara 2.8.8

### Description

We added an xfail to this [test]() in #6336. The issue is that this VI method is trying to replace an RV by a larger one. This is not allowed when the graph is created with a fixed size RV.

The test case doesn't seem needed at all, one can create a variable sized RV already with a shared variable and then resize it. Would this fulfill all the needs?