server: fix exception in DeploymentPlanningManagerImplTest (#6799)

previously
```
[INFO] Running com.cloud.deploy.DeploymentPlanningManagerImplTest

java.lang.NullPointerException
	at com.cloud.deploy.DeploymentPlanningManagerImpl.planDeployment(DeploymentPlanningManagerImpl.java:403)
	at com.cloud.deploy.DeploymentPlanningManagerImplTest.failEncRootLastHostNotSupportingEncryptionTest(DeploymentPlanningManagerImplTest.java:644)

...
[INFO] Tests run: 27, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.407 s - in com.cloud.deploy.DeploymentPlanningManagerImplTest

```

with this PR

```
[INFO] Running com.cloud.deploy.DeploymentPlanningManagerImplTest

[INFO] Tests run: 27, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.481 s - in com.cloud.deploy.DeploymentPlanningManagerImplTest
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 27, Failures: 0, Errors: 0, Skipped: 0
```

Author: weizhouapache

server/src/test/java/com/cloud/deploy/DeploymentPlanningManagerImplTest.java

@@ -193,6 +193,9 @@ public class DeploymentPlanningManagerImplTest {
     @Mock
     Host host;
 
+    @Mock
+    ConfigurationDao configDao;
+
     private static final long dataCenterId = 1L;
     private static final long instanceId = 123L;
     private static final long hostId = 0L;