Fix flaky DefaultResourceDataCacheTest.testGetCachedResourceData

Await cached resource data to become available after save eviction
before asserting, and await null after deletion. Prevents Mockito
verifyNoMoreInteractions(resourceService) failure caused by racing
background cache-load invocations.

Backport of 99334ba7fe from master.

application/src/test/java/org/thingsboard/server/service/resource/DefaultResourceDataCacheTest.java

@@ -15,6 +15,7 @@
  */
 package org.thingsboard.server.service.resource;
 
+import org.awaitility.Awaitility;
 import org.junit.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.test.context.bean.override.mockito.MockitoSpyBean;
@@ -29,6 +30,8 @@ import org.thingsboard.server.dao.resource.ResourceService;
 import org.thingsboard.server.dao.resource.TbResourceDataCache;
 import org.thingsboard.server.dao.service.DaoSqlTest;
 
+import java.util.concurrent.TimeUnit;
+
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.timeout;
@@ -61,6 +64,8 @@ public class DefaultResourceDataCacheTest extends AbstractControllerTest {
         TbResourceInfo savedResource = tbResourceService.save(resource);
         verify(resourceDataCache, timeout(2000).times(1)).evictResourceData(tenantId, savedResource.getId());
 
+        Awaitility.await().atMost(2, TimeUnit.SECONDS).untilAsserted(() ->
+                assertThat(resourceDataCache.getResourceDataInfoAsync(tenantId, savedResource.getId()).get()).isNotNull());
         TbResourceDataInfo cachedData = resourceDataCache.getResourceDataInfoAsync(tenantId, savedResource.getId()).get();
         assertThat(cachedData.getData()).isEqualTo(data);
         assertThat(JacksonUtil.treeToValue(cachedData.getDescriptor(), GeneralFileDescriptor.class)).isEqualTo(descriptor);
@@ -76,8 +81,8 @@ public class DefaultResourceDataCacheTest extends AbstractControllerTest {
         TbResource resourceById = resourceService.findResourceById(tenantId, savedResource.getId());
         tbResourceService.delete(resourceById, true, null);
         verify(resourceDataCache, timeout(2000).times(2)).evictResourceData(tenantId, savedResource.getId());
-        TbResourceDataInfo cachedDataAfterDeletion = resourceDataCache.getResourceDataInfoAsync(tenantId, savedResource.getId()).get();
-        assertThat(cachedDataAfterDeletion).isEqualTo(null);
+        Awaitility.await().atMost(2, TimeUnit.SECONDS).untilAsserted(() ->
+                assertThat(resourceDataCache.getResourceDataInfoAsync(tenantId, savedResource.getId()).get()).isNull());
     }
 
 }