Remove chrome_child.dll.pdb from isolate file because it's not there on the bots.

This is breaking after r295514 which enforces that every file listed in an isolate file exists.

BUG=414808
R=zmo@chromium.org

Review URL: https://codereview.chromium.org/574903003

Cr-Commit-Position: refs/heads/master@{#295547}

chrome/telemetry_gpu_test.isolate

@@ -30,7 +30,6 @@
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/chrome.exe.pdb',
-          '<(PRODUCT_DIR)/chrome_child.dll.pdb',
         ],
       },
     }],