chore: remove more unused fixtures

Author: cpcloud

ibis/backends/bigquery/tests/unit/udf/snapshots/test_core/test_scope_with_while/out.js

@@ -1,5 +1,5 @@
 function f() {
-    class Foo {
+    class _ {
         do_stuff() {
             while (true) {
                 let i = 1;

ibis/backends/bigquery/tests/unit/udf/snapshots/test_core/test_set_to_object/out.js

@@ -1,4 +1,4 @@
-function f(a) {
+function f(_) {
     let x = (new Set());
     let y = 1;
     x.add(y);

ibis/backends/bigquery/tests/unit/udf/snapshots/test_core/test_setitem/out.js

@@ -1,4 +1,4 @@
-function f(a) {
+function f(_) {
     let x = {};
     let y = '2';
     x[y] = y;

ibis/backends/bigquery/tests/unit/udf/snapshots/test_core/test_yield/out.js

@@ -1,3 +1,3 @@
-function* f(a) {
+function* f(_) {
     yield* [1, 2, 3];
 }

ibis/backends/bigquery/tests/unit/udf/test_usage.py

@@ -66,7 +66,7 @@ def my_len(s: str) -> float:
 def test_udf_int64(argument_type, return_type):
     # invalid argument type, valid return type
     @udf.scalar.python(signature=((argument_type,), return_type))
-    def my_func(_):
+    def my_func(_x):
         return 1
 
     expr = my_func(None)