Bug 1411358 - Increase Android/debug xpcshell max-run-time; r=me,a=test-only

Task run time for these tests is highly variable across chunks: Some run
in only 30 minutes, while xpcshell-11 sometimes exceeds 90 minutes.
Rather than waste resources on more chunks, I think increasing the max
task run time is a reasonable way of avoiding intermittent task time-outs.

taskcluster/ci/test/xpcshell.yml

@@ -50,7 +50,10 @@ xpcshell:
         by-test-platform:
             android.*: xlarge
             default: default
-    max-run-time: 5400
+    max-run-time:
+        by-test-platform:
+            android-4.3-arm7-api-16/debug: 7200
+            default: 5400
     e10s: false
     allow-software-gl-layers: false
     tier: