Update renamed Android ARM64 trybot in PRESUBMIT.py.

TBR=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/44209004

Cr-Commit-Position: refs/heads/master@{#9006}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 90ede51..7a51859 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -325,7 +325,7 @@
   ]
   android_bots = [
       'android',
-      'android_arm64',
+      'android_arm64_rel',
       'android_rel',
       'android_clang',
   ] + android_gn_bots