fix(ble): Fix onRead callback

[lucasssvaz]

Description of Change

This pull request updates the logic for handling GATT server read events in both BLECharacteristic and BLEDescriptor to ensure that the onRead() callback is only called for the initial read request, and not for follow-up packets during long reads. This prevents unnecessary repeated callbacks and makes the behavior more robust.

Improvements to GATT read event handling:

• Updated BLECharacteristic::handleGATTServerEvent to call onRead() only if the buffer length is greater than 0 and the connection handle is valid, ensuring callbacks are not triggered for follow-up packets in long reads.
• Updated BLEDescriptor::handleGATTServerEvent to use the same logic, only calling onRead() for the initial read request and not for follow-up packets, by checking buffer length and connection handle validity.

Test Scenarios

Tested locally

Related links

Fixes #12198

[github-actions]

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Generated by 🚫 dangerJS against f8e0947

[github-actions]

Test Results

 90 files   90 suites   33m 8s ⏱️
 67 tests  62 ✅ 0 💤 5 ❌
751 runs  745 ✅ 0 💤 6 ❌

For more details on these failures, see this check.

Results for commit f8e0947.

♻️ This comment has been updated with latest results.

[P-R-O-C-H-Y]

LGTM, CI is failing due to unused variable.

[lucasssvaz]

LGTM, CI is failing due to unused variable.

Fixed, thanks!

[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
ESP32	0	0	0.00	0.00	0	0	0.00	0.00
ESP32C3	💚 -272	0	💚 -0.04	0.00	0	0	0.00	0.00
ESP32C5	0	0	0.00	0.00	0	0	0.00	0.00
ESP32C6	0	0	0.00	0.00	0	0	0.00	0.00
ESP32H2	💚 -270	0	💚 -0.04	0.00	0	0	0.00	0.00
ESP32P4	💚 -270	0	💚 -0.03	0.00	0	0	0.00	0.00
ESP32S3	💚 -276	0	💚 -0.05	0.00	0	0	0.00	0.00

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

Target	ESP32		ESP32C3		ESP32C5		ESP32C6		ESP32H2		ESP32P4		ESP32S3
Example	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM
libraries/BLE/examples/Beacon_Scanner	0	0	💚 -268	0	-	-	-	-	💚 -268	0	💚 -268	0	💚 -276	0
libraries/BLE/examples/Client	0	0	💚 -262	0	-	-	-	-	💚 -262	0	💚 -262	0	💚 -240	0
libraries/BLE/examples/Client_Server	0	0	💚 -262	0	-	-	-	-	💚 -262	0	💚 -262	0	-	-
libraries/BLE/examples/Client_multiconnect	0	0	💚 -262	0	-	-	-	-	💚 -262	0	💚 -262	0	-	-
libraries/BLE/examples/Client_secure_static_passkey	0	0	💚 -262	0	-	-	-	-	💚 -262	0	💚 -262	0	-	-
libraries/BLE/examples/EddystoneTLM_Beacon	0	0	💚 -270	0	-	-	-	-	💚 -270	0	💚 -270	0	-	-
libraries/BLE/examples/EddystoneURL_Beacon	0	0	💚 -270	0	-	-	-	-	💚 -270	0	💚 -270	0	-	-
libraries/BLE/examples/Notify	0	0	💚 -264	0	-	-	-	-	💚 -262	0	💚 -262	0	-	-
libraries/BLE/examples/Scan	0	0	💚 -268	0	-	-	-	-	💚 -268	0	💚 -268	0	-	-
libraries/BLE/examples/Server	0	0	💚 -270	0	-	-	-	-	💚 -268	0	💚 -268	0	-	-
libraries/BLE/examples/Server_multiconnect	0	0	💚 -264	0	-	-	-	-	💚 -262	0	💚 -262	0	-	-
libraries/BLE/examples/Server_secure_static_passkey	0	0	💚 -272	0	-	-	-	-	💚 -270	0	💚 -270	0	-	-
libraries/BLE/examples/UART	0	0	💚 -262	0	-	-	-	-	💚 -262	0	💚 -264	0	-	-
libraries/BLE/examples/Write	0	0	💚 -270	0	-	-	-	-	💚 -268	0	💚 -268	0	-	-
libraries/BLE/examples/iBeacon	0	0	💚 -262	0	-	-	-	-	💚 -262	0	💚 -262	0	-	-
libraries/BLE/examples/Server_secure_authorization	-	-	💚 -264	0	-	-	-	-	💚 -264	0	-	-	-	-