Mark test_inline_vr_poses.html as single_test

This was missed when updating testharness.js as it is not a CQ-blocking
bot.

Bug: 1051025
Change-Id: Iebbab23d7ab123d1c4a4cbef9bab4bb5b5c0060f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2049907Reviewed-by: Luke Z <lpz@chromium.org>
Commit-Queue: Luke Z <lpz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#740365}

chrome/test/data/xr/e2e_test_files/html/test_inline_vr_poses.html

@@ -20,6 +20,8 @@ test can query for whether each submitted frame used the correct pose.
     <script src="../resources/webxr_e2e.js"></script>
     <script src="../resources/webxr_boilerplate.js"></script>
     <script>
+      setup({single_test: true});
+
       // Override the reference space map to only request eye-level stationary
       // reference spaces, as opposed to the identity MagicWindow/AR spaces.
       referenceSpaceMap = {