Ignore Time Machine XPC errors in desktop tests

Desktop tests on macOS failed due to XPC connection errors from Time
Machine backup services. These errors occur because Electron apps on
macOS automatically attempt to connect to system services in the
sandbox environment, even when they're not available in CI.

Added a regex pattern to STDERR_IGNORE_PATTERNS to prevent these
benign system messages from failing the tests. Also fixed a grammar
issue in an existing comment for Linux errors.

Author: undergroundwires

tests/checks/desktop-runtime-errors/check-desktop-runtime-errors/app/error-ignore-patterns.ts

@@ -29,7 +29,7 @@ export const STDERR_IGNORE_PATTERNS: readonly RegExp[] = [
   /*
     OS: Linux (GitHub Actions)
     Background:
-      Occur during Electron's GPU process initialization. Common in headless CI/CD environments.
+      These errors occur during during Electron's GPU process initialization. Common in headless CI/CD environments.
       Not indicative of a problem in typical desktop environments.
     Original logs:
       [3548:0828/162502.835833:ERROR:viz_main_impl.cc(186)] Exiting GPU process due to errors during initialization
@@ -38,4 +38,16 @@ export const STDERR_IGNORE_PATTERNS: readonly RegExp[] = [
   */
   /ERROR:viz_main_impl\.cc.*?Exiting GPU process due to errors during initialization/,
   /ERROR:command_buffer_proxy_impl\.cc.*?ContextResult::kTransientFailure: Failed to send GpuControl\.CreateCommandBuffer\./,
+
+  /*
+   OS: macOS (GitHub Actions)
+   Background:
+      Time Machine backup service XPC connection errors occur in CI environments.
+      These errors happen because Electron apps on macOS automatically attempt to
+      connect to system services even when they're not available in CI.
+   Original logs:
+      2025-04-07 09:31:01.530 privacy.sexy Helper[15420:39156] XPC error for connection com.apple.backupd.sandbox.xpc: Connection invalid
+      2025-04-07 09:31:01.530 privacy.sexy Helper[15420:39151] XPC error for connection com.apple.backupd.sandbox.xpc: Connection invalid
+  */
+  /privacy\.sexy Helper\[\d+:\d+\] XPC error for connection com\.apple\.backupd\.sandbox\.xpc: Connection invalid/,
 ];