Change w value for unsatisfiable write concern in tests (#301)

- Addresses test failures that started after by SERVER-45920

Author: Divjot Arora

mongo/integration/collection_test.go

@@ -39,7 +39,7 @@ func TestCollection(t *testing.T) {
 	// impossibleWc is a write concern that can't be satisfied and is used to test write concern errors
 	// for various operations. It includes a timeout because legacy servers will wait for all W nodes to respond,
 	// causing tests to hang.
-	impossibleWc := writeconcern.New(writeconcern.W(500), writeconcern.WTimeout(time.Second))
+	impossibleWc := writeconcern.New(writeconcern.W(30), writeconcern.WTimeout(time.Second))
 
 	mt.RunOpts("insert one", noClientOpts, func(mt *mtest.T) {
 		mt.Run("success", func(mt *mtest.T) {