network_WiFi_BT_AntennaCoex: move from flaky suite

The test seems reasonably stable, so move from wifi_flaky to
wifi_matfunc.

BUG=chromium:876920
TEST=None
Signed-off-by: Kirtika Ruchandani <kirtika@google.com>

Change-Id: Icba4c8d14ea64bac8bffa4aeaeafaf74ee4344c0
Reviewed-on: https://chromium-review.googlesource.com/1577840
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Kirtika Ruchandani <kirtika@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Harpreet Grewal <harpreet@chromium.org>
diff --git a/server/site_tests/network_WiFi_BT_AntennaCoex/control b/server/site_tests/network_WiFi_BT_AntennaCoex/control
index 801c93f..8dc2b9a 100644
--- a/server/site_tests/network_WiFi_BT_AntennaCoex/control
+++ b/server/site_tests/network_WiFi_BT_AntennaCoex/control
@@ -6,7 +6,7 @@
 NAME = 'network_WiFi_BT_AntennaCoex'
 TIME = 'SHORT'
 TEST_TYPE = 'Server'
-ATTRIBUTES = ('suite:wifi_flaky')
+ATTRIBUTES = ('suite:wifi_matfunc')
 DEPENDENCIES = 'wificell, bluetooth'
 
 DOC = """