Update DynamicConfigPusher to find files using CompatibilityBuildHelper

* The dynamic config may be in the general test case folder so
  we need to use the CompatibilityBuildHelper to find it.

Bug: 65490501
Test: tradefed.sh run template/local_min --template:map test=PtsWifiTestCases
Change-Id: I455da2909d0fc011de9eef1ba5c42724adc30fda
diff --git a/common/host-side/tradefed/src/com/android/compatibility/common/tradefed/targetprep/DynamicConfigPusher.java b/common/host-side/tradefed/src/com/android/compatibility/common/tradefed/targetprep/DynamicConfigPusher.java
index d64c210..2d0e361 100644
--- a/common/host-side/tradefed/src/com/android/compatibility/common/tradefed/targetprep/DynamicConfigPusher.java
+++ b/common/host-side/tradefed/src/com/android/compatibility/common/tradefed/targetprep/DynamicConfigPusher.java
@@ -86,7 +86,7 @@
 
         File localConfigFile = null;
         try {
-            localConfigFile = DynamicConfig.getConfigFile(buildHelper.getTestsDir(), mModuleName);
+            localConfigFile = buildHelper.getTestFile(mModuleName + ".dynamic");
         } catch (FileNotFoundException e) {
             throw new TargetSetupError("Cannot get local dynamic config file from test directory",
                     e, device.getDeviceDescriptor());