bluetooth: Initialize active_test_devices before each test

A corner case where tests weren't run but cleanup still occurs
resulted in a test error. This change ensures the proper data
structure is in place in all cases.

BUG=b:146561640
TEST=QuickSanity on raspberry pi and fizz, and individual test w/missing peer

Change-Id: If1d8e5b1de4fa21322c084f29fdd0354976c5c0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1976074
Reviewed-by: Yun-Hao Chung <howardchung@google.com>
Tested-by: Daniel Winkler <danielwinkler@google.com>
Commit-Queue: Daniel Winkler <danielwinkler@google.com>
diff --git a/server/cros/bluetooth/bluetooth_adapter_quick_tests.py b/server/cros/bluetooth/bluetooth_adapter_quick_tests.py
index bf2718f..fe34dc5 100644
--- a/server/cros/bluetooth/bluetooth_adapter_quick_tests.py
+++ b/server/cros/bluetooth/bluetooth_adapter_quick_tests.py
@@ -108,6 +108,9 @@
                 self.chameleon_group_copy = dict()
                 self.group_chameleons_type()
 
+        # Clear the active devices for this test
+        self.active_test_devices = {}
+
         self.enable_disable_debug_log(enable=True)
 
         self.flag = flag