fix(httpc): Fix data read was less than expected

[me-no-dev]

Data read from the client might actually be less than what we requested. Use the proper count when calculating data lengths.

Fixes: #9997

[github-actions]

	Messages
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Generated by 🚫 dangerJS against 122881f

[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	💚 -4	0	0.00	0.00	0	0	0.00	0.00
ESP32S2	💚 -12	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	💚 -20	0	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
HTTPClient/examples/Authorization	0	0	💚 -12	0	0	0	0	0	💚 -20	0
HTTPClient/examples/BasicHttpClient	0	0	💚 -12	0	0	0	0	0	💚 -20	0
HTTPClient/examples/BasicHttpsClient	0	0	💚 -12	0	0	0	0	0	💚 -20	0
HTTPClient/examples/HTTPClientEnterprise	0	0	💚 -12	0	0	0	0	0	💚 -20	0
HTTPClient/examples/ReuseConnection	0	0	💚 -12	0	0	0	0	0	💚 -20	0
HTTPClient/examples/StreamHttpClient	💚 -4	0	💚 -4	0	0	0	0	0	💚 -4	0

[github-actions]

Test Results

 56 files  ±0   56 suites  ±0   4m 55s ⏱️ -23s
 21 tests ±0   21 ✅ ±0  0 💤 ±0  0 ❌ ±0 
135 runs  ±0  135 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 122881f. ± Comparison against base commit 4e3523c.

♻️ This comment has been updated with latest results.