fix: drop removed len argument from ScalarFnArray::try_new call

ScalarFnArray::try_new lost its len parameter in #8378 and now infers
the length from the first child, which matches the old behavior of
passing a.len().

DCO Remediation Commit for Nemo Yu <zyu379@wisc.edu>

I, Nemo Yu <zyu379@wisc.edu>, hereby add my Signed-off-by to this commit: 88cb5a2
I, Nemo Yu <zyu379@wisc.edu>, hereby add my Signed-off-by to this commit: 8789430
I, Nemo Yu <zyu379@wisc.edu>, hereby add my Signed-off-by to this commit: 549f5c4
I, Nemo Yu <zyu379@wisc.edu>, hereby add my Signed-off-by to this commit: ec95875
I, Nemo Yu <zyu379@wisc.edu>, hereby add my Signed-off-by to this commit: 874c171

Signed-off-by: Nemo Yu <zyu379@wisc.edu>

Author: HarukiMoriarty

vortex-geo/src/scalar_fn/distance.rs

@@ -46,11 +46,9 @@ impl GeoDistance {
     /// A lazy `ScalarFnArray` computing the per-row distance between the point columns `a` and
     /// `b`; either may be constant. The output length is taken from `a`.
     pub fn try_new_array(a: ArrayRef, b: ArrayRef) -> VortexResult<ScalarFnArray> {
-        let len = a.len();
         ScalarFnArray::try_new(
             TypedScalarFnInstance::new(GeoDistance, EmptyOptions).erased(),
             vec![a, b],
-            len,
         )
     }
 }