discovery does not send 'hello' as first command

[ben-qnimble]

Per the specification for pluggable discovery (https://arduino.github.io/arduino-cli/0.20/pluggable-discovery-specification/):

HELLO must be the first command sent to the discovery

but the 1.x Arduino IDE does not send the hello command. On starting a discovery, the first command it sends is START_SYNC which fails for serial-discovery and discoveries based on it because they catch and error when the first command is not hello:

$ /packages/builtin/tools/serial-discovery/1.3.1/serial-discovery.exe
START_SYNC
{
  "eventType": "command_error",
  "message": "First command must be HELLO, but got 'START_SYNC'",
  "error": true
}

The arduino-cli does send the HELLO command first so this is not a problem in Arduino IDE 2.x, and I believe Arduino IDE 1.x should match this behavior.