Fix implicit Node to Output conversion in transformations

[evkotov]

Details:

This PR fixes implicit Node to Output conversion issues found left after #30337

Changes:

• lora_subgraph_horizontal_fusion.cpp: Use input_value() instead of get_input_node_shared_ptr() when filling OutputVector for LoraSubgraphFused constructor
• propagate_precision.cpp: Use input_value() instead of get_input_node_shared_ptr() when creating ConvertSaturation node

These issues are classified as non-critical because the inputs are typically single-output nodes (ReadValue, Convert, etc.) and don't cause exceptions in real scenarios. However, they violate the best practice of avoiding implicit conversions when creating nodes.

Tickets:

• 165972