Temporarily remove tests that fail running with a single GPU. (#5100)

* Temporarily remove tests that fail running with a single GPU.

* Fix tags order according to buildifier

tensorflow/contrib/training/BUILD

@@ -36,6 +36,7 @@ py_test(
     size = "medium",
     srcs = ["python/training/batch_sequences_with_states_test.py"],
     srcs_version = "PY2AND3",
+    tags = ["manual"],
     deps = [
         ":training_py",
         "//tensorflow:tensorflow_py",
@@ -60,7 +61,10 @@ py_test(
     size = "small",
     srcs = ["python/training/sampling_ops_threading_test.py"],
     srcs_version = "PY2AND3",
-    tags = ["notsan"],
+    tags = [
+        "manual",
+        "notsan",
+    ],
     deps = [
         ":training_py",
         "//tensorflow:tensorflow_py",
@@ -73,6 +77,7 @@ py_test(
     size = "medium",
     srcs = ["python/training/bucket_ops_test.py"],
     srcs_version = "PY2AND3",
+    tags = ["manual"],
     deps = [
         ":training_py",
         "//tensorflow:tensorflow_py",