revert sqrt change

Author: tswast

bigframes/core/compile/polars/operations/numeric_ops.py

@@ -88,4 +88,4 @@ def sqrt_op_impl(
 ) -> pl.Expr:
     import polars as pl
 
-    return pl.when(input <= 0).then(float("nan")).otherwise(input.sqrt())
+    return pl.when(input < 0).then(float("nan")).otherwise(input.sqrt())

bigframes/core/compile/sqlglot/expressions/numeric_ops.py

@@ -207,7 +207,7 @@ def _(expr: TypedExpr) -> sge.Expression:
     return sge.Case(
         ifs=[
             sge.If(
-                this=expr.expr <= sge.convert(0),
+                this=expr.expr < sge.convert(0),
                 true=constants._NAN,
             )
         ],