cobalt/test: Fix Navigation Browser Tests for Android (#6837)

This change corrects missing data files and serving issues for nav
browser tests.
This keeps these tests disabled for non-Android builds. Since these
tests take a significant amount of time to run, follow-up PRs will
enable these for other platforms.

Test: out/android-arm_devel/bin/run_cobalt_browsertests -v
Bug: 432503432

Author: Awallky

cobalt/testing/browser_tests/BUILD.gn

@@ -346,7 +346,7 @@ test("cobalt_browsertests") {
   ]
 
   data = [
-    "data/",
+    "//content/test/data/",
     "//media/test/data/",
   ]