fix(examples): repair parser-blocking indentation and frame buffer encoding in EtherSenseServer

[magqqgq]

Description

This PR addresses medium-severity code cleanliness and resource handling defects within the librealsense Ethernet client-server example[cite: 16]. It repairs parser-blocking indentation errors, standardizes the transmitted frame buffer to strictly use bytes, and removes an invalid unused accept handler[cite: 16].

Key Changes

• Executable Correctness (wrappers/python/examples/ethernet_client_server/EtherSenseServer.py):
  • Fixed parser-blocking indentation issues that previously prevented the script from compiling and running[cite: 16].
  • Removed an unused accept-handler path that contained references to undefined data[cite: 16].
• Resource & Data Handling (EtherSenseServer.py):
  • Initialized self.frame_data as a byte string (b"")[cite: 21].
  • Standardized the update_frame method so that the protocol fields (length, timestamp, and pickled depth data) are consistently packed and concatenated strictly as bytes using struct.pack and pickle.dumps, resolving a previous defect that mixed text and bytes[cite: 16, 21].

Validation & Testing

• Syntax Validation: The modified Python file successfully passes AST parsing without indentation or syntax errors[cite: 16].
• Hardware Limitations: Hardware and network-runtime behavior remain unverified because the native RealSense hardware toolchains and device dependencies are unavailable in the current test environment[cite: 16].