Revert of CQ: Remove Linux ARM64 Debug trybot from default set.

infra/config/cq.cfg

Index: infra/config/cq.cfg
diff --git a/infra/config/cq.cfg b/infra/config/cq.cfg
index 64560e4ea641dab35c17f451d3073cde629ff751..e12f3c3096e10ad2fac6062674eeb14485624df9 100644
--- a/infra/config/cq.cfg
+++ b/infra/config/cq.cfg
@@ -47,8 +47,7 @@
       # TODO(kjellander): Add when bugs.webrtc.org/7090 is fixed.
       #builders { name: "linux32_arm_dbg" }
       builders { name: "linux32_arm_rel" }
-      # TODO(kjellander): Re-enable when it builds again (crbug.com/708104).
-      #builders { name: "linux_arm64_dbg" }
+      builders { name: "linux_arm64_dbg" }
       builders { name: "linux_arm64_rel" }
       builders { name: "linux_asan" }
       builders { name: "linux_baremetal" }