SCB-2176 Refactor websocket (#986)

[little-cui]

• SCB-2176 Refactor event bus

• SCB-2176 Fix: UT failures

• SCB-2176 Refactor websocket (SCB-2176 Refactor websocket #980)

• SCB-2176 Refactor websocket

• SCB-2176 Add UTs

• SCB-2176 Fix: UT failures

• SCB-2176 Fix: websocket health check failed

• SCB-2176 Add benchmark for 10K connection

• SCB-2176 Add benchmark for 10K connection

• SCB-2176 Add event metrics

(cherry picked from commit cc0f684)

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