test: remove testIncompatibleVersionDataStreamSet

ES 7 is no longer supported. The test was asserting a data-stream
version check that was removed in 52f1fab, making it dead code.

Author: yeikel

src/test/java/io/confluent/connect/elasticsearch/ValidatorTest.java

@@ -488,18 +488,6 @@ public void testTimestampMappingDataStreamNotSet() {
     assertHasErrorMessage(result, DATA_STREAM_TIMESTAMP_CONFIG, TIMESTAMP_FIELD_NOT_ALLOWED_ERROR);
   }
 
-  @Test
-  public void testIncompatibleVersionDataStreamSet() throws IOException {
-    configureDataStream();
-    validator = new Validator(props, () -> mockClient);
-    when(mockClient.info().version().number()).thenReturn("7.8.1");
-
-    Config result = validator.validate();
-    assertHasErrorMessage(result, CONNECTION_URL_CONFIG, "not compatible with data streams");
-    assertHasErrorMessage(result, DATA_STREAM_TYPE_CONFIG, "not compatible with data streams");
-    assertHasErrorMessage(result, DATA_STREAM_DATASET_CONFIG, "not compatible with data streams");
-  }
-
   @Test
   public void testIncompatibleVersionDataStreamNotSet() throws IOException {
     validator = new Validator(props, () -> mockClient);