Bug 1982318 - Fix some flakiness in the about:logging tests r=julienw

Previously, when we were saving the profile to disk, we getting the
profile path from the localized string. But it appears that due to some
rendering timing issues, the rendered text might not contain the path
yet. But we will always have it inside the data-l10n-args attribute.
That's why it's better to check that directly.

Differential Revision: https://phabricator.services.mozilla.com/D261090

Author: canova

toolkit/content/tests/browser/browser_about_logging.js

@@ -587,10 +587,19 @@ add_task(async function testAndroidUI() {
     info("Click the save button");
     const saveButton = await getElementFromDocumentByText(document, "Save");
     EventUtils.synthesizeMouseAtCenter(saveButton, {}, window);
+
     const savedText = await getElementFromDocumentByText(document, "Saved to");
     ok(savedText, "The text path is being displayed");
-    info(`The text displayed is: ${savedText.textContent}`);
-    const savedPath = savedText.textContent.slice("Saved to ".length);
+
+    // Extract the file path from the l10n arguments
+    const savedPath = JSON.parse(savedText.getAttribute("data-l10n-args")).path;
+    info(`Profile saved to: ${savedPath}`);
+
+    Assert.ok(
+      savedPath && !!savedPath.length,
+      "Saved path should not be empty"
+    );
+
     const fileinfo = await IOUtils.stat(savedPath);
     Assert.greater(
       fileinfo.size,