Several fixes around Chunk processing (Json) of a large Json document and available length passed to fill send buffer #496

Job	Run time
ESP32 (arduino-cli) - Release	39s
ESP32 (arduino-cli) - Dev	39s
ESP32 (pio) - Arduino 2 (esp32-s3-devkitc-1)	39s
ESP32 (pio) - Arduino 2 (esp32-s2-saola-1)	39s
ESP32 (pio) - Arduino 2 (esp32-c3-devkitc-02)	40s
ESP32 (pio) - Arduino 2 (esp32dev)	39s
ESP32 (pio) - Specific Envs (ci-no-json)	1s
ESP32 (pio) - Specific Envs (ci-latest-asynctcp)	1s
ESP32 (pio) - Specific Envs (ci-arduino-2-esp-idf-log)	40s
ESP32 (pio) - Specific Envs (ci-regex)	29s
ESP32 (pio) - Arduino 3 (esp32-c3-devkitc-02)	1s
ESP32 (pio) - Arduino 3 (esp32-s2-saola-1)	1s
ESP32 (pio) - Arduino 3 (esp32dev)	1s
ESP32 (pio) - Specific Envs (ci-no-chunk-inflight)	29s
ESP32 (pio) - Arduino 3 (esp32-s3-devkitc-1)	1s
ESP32 (pio) - Arduino 3 (esp32-c6-devkitc-1)	28s
ESP32 (pio) - Arduino 3 (esp32-h2-devkitm-1)	1s
ESP32 (pio) - Specific Envs (ci-arduino-3-esp-idf-log)	30s
ESP32 (pio) - Arduino 3 (esp32-p4)	28s
	7m 6s

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