Change at.zeros to at.empty when creating combined observed/missi…

…ng vector

Co-authored-by: Ricardo Vieira <28983449+ricardoV94@users.noreply.github.com>

pymc/model.py

@@ -1456,7 +1456,7 @@ def make_obs_var(
 
             # Create deterministic that combines observed and missing
             # Note: This can widely increase memory consumption during sampling for large datasets
-            rv_var = at.zeros(data.shape, dtype=observed_rv_var.type.dtype)
+            rv_var = at.empty(data.shape, dtype=observed_rv_var.type.dtype)
             rv_var = at.set_subtensor(rv_var[mask.nonzero()], missing_rv_var)
             rv_var = at.set_subtensor(rv_var[antimask_idx], observed_rv_var)
             rv_var = Deterministic(name, rv_var, self, dims)