ArduinoOTA - change occurrence of client.flush() to clear()

[JAndrassy]

as follow up of changing flush() to clear() in networking with PR #9453, there is an unclear use of flush() in ArduinoOTA.

The UDP object in ArduinoOTA is used to receive and send messages in handle(). The function _onRx invoked in handle() before flush()) reads a message and then sends a response. So it is unclear what the flush() in handle() was meant to do.

But the library would fail if for some reason _onRx doesn't read the whole incoming message because then all following parsePacket will always return 0 (and this is not a good behavior of the NetworkUDP class).

[github-actions]

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Generated by 🚫 dangerJS against 8666de1

[github-actions]

Memory usage test (comparing PR against master branch)

The table below shows the summary of memory usage change (decrease - increase) in bytes and percentage for each target.

Memory	FLASH [bytes]		FLASH [%]		RAM [bytes]		RAM [%]
Target	DEC	INC	DEC	INC	DEC	INC	DEC	INC
ESP32S3	0	⚠️ +32	0.00	0.00	0	0	0.00	0.00
ESP32S2	0	⚠️ +36	0.00	0.00	0	0	0.00	0.00
ESP32C3	0	⚠️ +34	0.00	0.00	0	0	0.00	0.00
ESP32C6	0	⚠️ +34	0.00	0.00	0	0	0.00	0.00
ESP32	0	⚠️ +32	0.00	0.00	0	0	0.00	0.00

Click to expand the detailed deltas report [usage change in BYTES]

Target	ESP32S3		ESP32S2		ESP32C3		ESP32C6		ESP32
Example	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM
ArduinoOTA/examples/BasicOTA	⚠️ +32	0	⚠️ +36	0	⚠️ +34	0	⚠️ +34	0	⚠️ +32	0

[github-actions]

Test Results

 56 files   -  83   56 suites   - 83   5m 16s ⏱️ - 1h 37m 53s
 21 tests  -   9   21 ✅  -   9  0 💤 ±0  0 ❌ ±0 
135 runs   - 168  135 ✅  - 168  0 💤 ±0  0 ❌ ±0 

Results for commit 8666de1. ± Comparison against base commit cd3d0bf.

This pull request removes 9 tests.

performance.coremark.test_coremark ‑ test_coremark
performance.fibonacci.test_fibonacci ‑ test_fibonacci
performance.psramspeed.test_psramspeed ‑ test_psramspeed
performance.ramspeed.test_ramspeed ‑ test_ramspeed
performance.superpi.test_superpi ‑ test_superpi
test_touch_errors
test_touch_interrtupt
test_touch_read
validation.periman.test_periman ‑ test_periman

♻️ This comment has been updated with latest results.