Remove now redundant variant property

Previously, this was useful for discriminating between different
`CodeQLDefaultVersion` instances. However now all instances return a
tag name.

src/testing-utils.ts

@@ -15,7 +15,7 @@ import {
   FeatureEnablement,
 } from "./feature-flags";
 import { Logger } from "./logging";
-import { GitHubVariant, HTTPError } from "./util";
+import { HTTPError } from "./util";
 
 export const SAMPLE_DOTCOM_API_DETAILS = {
   auth: "token",
@@ -26,7 +26,6 @@ export const SAMPLE_DOTCOM_API_DETAILS = {
 export const SAMPLE_DEFAULT_CLI_VERSION: CodeQLDefaultVersionInfo = {
   cliVersion: "2.20.0",
   tagName: "codeql-bundle-v2.20.0",
-  variant: GitHubVariant.DOTCOM,
 };
 
 type TestContext = {