chore: fix tests that check package versions in the pipeline (#26934)

They execute correctly locally and in a PR build, but not in the Pipeline because the `framework-integ` package gets an `-alpha.999` suffix (whereas the actual constructs get an `-rc.0` suffix).

The test used to read the expected version from its own `package.json`. It will now read the expected version from `aws-cdk-lib`'s `package.json`.

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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: rix0rrr

packages/@aws-cdk-testing/framework-integ/test/core/test/runtime-info.test.ts

@@ -176,7 +176,7 @@ class TestConstruct extends Construct {
 function localCdkVersion(): string {
   if (!_cdkVersion) {
     // eslint-disable-next-line @typescript-eslint/no-require-imports
-    const pkgJson = findParentPkgJson(__dirname);
+    const pkgJson = findParentPkgJson(require.resolve('aws-cdk-lib'));
     _cdkVersion = pkgJson.version;
     if (!_cdkVersion) {
       throw new Error('Unable to determine CDK version');