Add missing slash to payments data dependency.

Without this, isolate.py fails.

python tools/swarming_client/isolate.py check -i out/Android-arm-dbg/android_browsertests.isolate -s out/Android-arm-dbg/android_browsertests.isolated
Failed to find an input file: Input directory /usr/local/google/home/fergal/chromium/src/components/test/data/payments must have a trailing slash
  -> returned 1

Change-Id: I624016f2711038ad0f7920cac645e1b2c3d0f045
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1871159Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707742}

chrome/test/BUILD.gn

@@ -544,7 +544,7 @@ if (is_android) {
       "$root_gen_dir/chrome/android/chrome_apk_paks/resources.pak",
       "$root_gen_dir/components/components_resources.pak",
       "$root_out_dir/browser_tests.pak",
-      "//components/test/data/payments",
+      "//components/test/data/payments/",
     ]
   }