[TF FE][Tests] Fix non-deterministic FILM model test failure (#33977)
### Details:
The test `test_tf_hub_api_notebook1[CPU-film]` was failing randomly in
CI with shape mismatch error:
ValueError: operands could not be broadcast together with shapes
(1,200,200,2) (1,6,6,2)
Root cause: The test used `list(film_layer.values())[0]` to select the
model output. This is incorrect because:
1. Python dict iteration order depends on hash randomization
(PYTHONHASHSEED), which is random by default since Python 3.3
2. The FILM model returns 7 different outputs including flow pyramids
with various shapes
3. When dict iteration returns a flow pyramid instead of 'image', the
shapes don't match
The fix selects the output by name (`film_layer['image']`) instead of by
position.
### Why the fix is in the test, not in OpenVINO TF Frontend
Fixing this in OpenVINO is not possible because TensorFlow itself does
not guarantee output order:
1. SavedModel signature uses protobuf `map<string, TensorInfo>` for
outputs, which has no defined iteration order per protobuf specification
2. TensorFlow documentation states that signature inputs/outputs are
"identified by string names", not by position
3. Even within pure TensorFlow (without OpenVINO), the dict key order
changes between runs depending on PYTHONHASHSEED
OpenVINO cannot preserve an order that TensorFlow does not define. The
only reliable way to select a specific output is by name.
### Tickets:
- 180301
openvino
af2bd6fa - [TF FE][Tests] Fix non-deterministic FILM model test failure (#33977)
