test: fix windows environment and cleanup issues

- Ensure 'SystemRoot', 'COMSPEC', 'windir', and 'PATHEXT' are passed to node-pty on Windows to prevent 'posix_spawnp' failures.
- Clean up test directories in 'TestRig.setup' to ensure a fresh state for retries and prevent telemetry log accumulation (fixing the 1, 2, 3 failure pattern).
- Fix path normalization in 'Hook Disabling' test to ensure disabled hooks are correctly matched on Windows.

Part of https://github.com/google-gemini/gemini-cli/pull/18665

integration-tests/hooks-system.test.ts

@@ -1831,7 +1831,7 @@ console.log(JSON.stringify({decision: "block", systemMessage: "Disabled hook sho
         settings: {
           hooksConfig: {
             enabled: true,
-            disabled: [`node "${disabledPath}"`], // Disable the second hook
+            disabled: [normalizePath(`node "${disabledPath}"`)], // Disable the second hook
           },
           hooks: {
             BeforeTool: [