fix(throttle): avoid duplicate cruise command

[zjwhitehead]

Summary

• remove the duplicate ESC throttle request emitted during every ARMED_CRUISING control iteration
• keep cruise handling focused on override/disengagement state changes
• retain the common, relay-aware ESC send path as the sole command publisher

Why

Cruise mode currently queues the same throttle command once inside handleCruisingThrottle() and again through handleThrottle()'s common send path. This doubles cruise-mode CAN command and response work inside the 50 Hz control task without changing the requested throttle.

Validation

• pio test -e native-test: 60 passed
• ./test/test_screenshots/build_and_run.sh: 34 passed
• pio run -e OpenPPG-CESP32S3-CAN-SP140: successful target build

[zjwhitehead]

LGTM. Cruise now publishes only through the shared relay-aware setESCThrottle path. Override behavior is unchanged.

(Could not formally approve: GitHub blocks self-approval on your own PR.)

[zjwhitehead]

Hardware-in-loop validation (M5Stack StampS3 over USB, no ESC/BMS connected): instrumented baseline produced 251 cruise control cycles and 502 high-level throttle commands in a full 5.0 s safe dry-cruise window. This PR produced 251 cycles and 251 commands. Control cadence remained 50 Hz, free heap was unchanged at 100,892 bytes, LVGL redraw traffic completed with 0 skipped flushes, and the controller restored to DISARMED after the 10 s probe. ESC transmission was explicitly suppressed at setESCThrottle for the probe. This confirms the duplicate-command hypothesis and the intended 50% reduction in cruise command work on real hardware.