refactor(http-client): Replace USE_SERIAL with direct Serial

[JakubAndrysek]

Description of Change

Replace USE_SERIAL macro with direct Serial calls in HTTPClient examples

Test Scenarios

Tested on master

Related links

#11768 (comment)

[github-actions]

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[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
ESP32C5	0	0	0.00	0.00	0	0	0.00	0.00
ESP32P4	0	0	0.00	0.00	0	0	0.00	0.00
ESP32S3	0	0	0.00	0.00	0	0	0.00	0.00
ESP32S2	0	0	0.00	0.00	0	0	0.00	0.00
ESP32C3	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
ESP32	0	0	0.00	0.00	0	0	0.00	0.00

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

Target	ESP32C5		ESP32P4		ESP32S3		ESP32S2		ESP32C3		ESP32C6		ESP32
Example	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM	FLASH	RAM
libraries/HTTPClient/examples/Authorization	-	-	-	-	-	-	-	-	-	-	-	-	-	-
libraries/HTTPClient/examples/BasicHttpClient	-	-	-	-	-	-	-	-	-	-	-	-	-	-
libraries/HTTPClient/examples/ReuseConnection	-	-	-	-	-	-	-	-	-	-	-	-	-	-
libraries/HTTPClient/examples/StreamHttpClient	-	-	-	-	-	-	-	-	-	-	-	-	-	-