[TF FE] Test TextVectorization on white-space string input and Equal …

…on empty string tensor (openvinotoolkit#23572)

**Details:** Test `tf.keras.TextVectorization` on white-space string
input and Equal on empty string tensor.

**Ticket:** 135749

---------

Signed-off-by: Kazantsev, Roman <roman.kazantsev@intel.com>

tests/layer_tests/tensorflow_tests/test_tf_Equal.py

@@ -241,8 +241,8 @@ def create_equal_net(self, x_shape, y_shape):
 
         return tf_net, ref_net
 
-    @pytest.mark.parametrize('x_shape', [[1], [5]])
-    @pytest.mark.parametrize('y_shape', [[1], [5]])
+    @pytest.mark.parametrize('x_shape', [[], [1], [5]])
+    @pytest.mark.parametrize('y_shape', [[], [1], [5]])
     @pytest.mark.precommit_tf_fe
     @pytest.mark.nightly
     @pytest.mark.xfail(condition=platform.system() in ('Darwin', 'Linux') and platform.machine() in ['arm', 'armv7l',