Fix semantic conflict in vortex-array (#8312)

## Summary

Fixes a minor semantic conflict introduced by some recent PRs.

Signed-off-by: Adam Gutglick <adam@spiraldb.com>

Author: AdamGS

vortex-array/src/arrays/constant/vtable/canonical.rs

@@ -787,7 +787,7 @@ mod tests {
         let element_validity = elements
             .validity()
             .vortex_expect("constant canonical element validity should be derivable");
-        let mut ctx = LEGACY_SESSION.create_execution_ctx();
+
         assert!(element_validity.execute_is_valid(0, &mut ctx).unwrap());
         assert!(!element_validity.execute_is_valid(1, &mut ctx).unwrap());
         assert!(element_validity.execute_is_valid(2, &mut ctx).unwrap());

vortex-array/src/arrays/listview/rebuild.rs

@@ -9,6 +9,7 @@ use vortex_error::VortexResult;
 use crate::Canonical;
 use crate::ExecutionCtx;
 use crate::IntoArray;
+use crate::LEGACY_SESSION;
 use crate::arrays::ConstantArray;
 use crate::arrays::ListViewArray;
 use crate::arrays::PrimitiveArray;
@@ -19,6 +20,7 @@ use crate::builtins::ArrayBuiltins;
 use crate::dtype::IntegerPType;
 use crate::dtype::Nullability;
 use crate::dtype::PType;
+use crate::executor::VortexSessionExecute;
 use crate::match_each_integer_ptype;
 use crate::match_each_unsigned_integer_ptype;
 use crate::scalar::Scalar;
@@ -484,7 +486,7 @@ mod tests {
 
         // Verify nullability is preserved
         assert_eq!(flattened.dtype().nullability(), Nullability::Nullable);
-        let mut ctx = LEGACY_SESSION.create_execution_ctx();
+        let mut ctx = SESSION.create_execution_ctx();
         assert!(flattened.validity()?.execute_is_valid(0, &mut ctx)?);
         assert!(!flattened.validity()?.execute_is_valid(1, &mut ctx)?);
         assert!(flattened.validity()?.execute_is_valid(2, &mut ctx)?);