Add back ImportStateVerifyIgnore

This is redis6.x specific. It has nothing to do with my DiffSuppressFunc changes or removing the lifecycle { ignore_changes } blocks. Still needed to pass tests :)

```
Step 2/2 error running import: ImportStateVerify attributes not equivalent. Difference is shown below. The - symbol indicates attributes missing after import.

          map[string]string{
        -       "engine_version": "6.x",
        +       "engine_version": "6.2",
          }
```

Author: twelsh-aw

internal/service/elasticache/global_replication_group_test.go

@@ -926,9 +926,10 @@ func TestAccElastiCacheGlobalReplicationGroup_SetEngineVersionOnCreate_NoChange_
 				),
 			},
 			{
-				ResourceName:      resourceName,
-				ImportState:       true,
-				ImportStateVerify: true,
+				ResourceName:            resourceName,
+				ImportState:             true,
+				ImportStateVerify:       true,
+				ImportStateVerifyIgnore: []string{names.AttrEngineVersion},
 			},
 		},
 	})