[llvm] [Hexagon] Fix hexagon-copy-hoisting.mir (PR #90740)

[via llvm-commits]

================
@@ -11,23 +11,19 @@
 
 ---
 name:            f0
-tracksRegLiveness: true
+tracksRegLiveness: false
----------------
mikaelholmen wrote:

Now, I don't know the Hexagon backend so I don't know if liveness should be tracked here or not. But a simple grep of tracksRegLiveness in  test/CodeGen/Hexagon shows that all already existing mir tests have
```
tracksRegLiveness: true
```
so simply disabling it for this testcase looks very suspicious to me.

https://github.com/llvm/llvm-project/pull/90740