revert(build-tools): Include ".generated" in typetest filenames (#12571)

This reverts commit 7f6cb54.

I need to do a more involved change that is easier to integrate with
other release groups. In particular, the generated names need to be
configurable.

build-tools/packages/build-tools/src/typeValidator/testGeneration.ts

@@ -109,7 +109,7 @@ export async function generateTests(packageDetails: PackageDetails) {
             `${testPath}/validate${oldVersionNameForFile
                 .split("-")
                 .map((p) => p[0].toUpperCase() + p.substring(1))
-                .join("")}.generated.ts`,
+                .join("")}.ts`,
             testString.join("\n"),
         );
     }