fix core: double truncation in request logging

[rjazhenka1]

Problem:

Request and response body logs are truncated twice, which results in (truncated, total X bytes) message having an incorrect size value (roughly around request_body_size_log_limit / response_data_size_log_limit).

1st truncation happens in GetRequestBodyForLogging() and GetResponseDataForLogging() (the resulting string is bigger than the limit due to the (truncated...) message).

2nd truncation happens in GetRequestBodyForLoggingChecked() and GetResponseDataForLoggingChecked(). Since the string from the 1st truncation is bigger than the limit, the string is truncated again and incorrect size is shown in the message.

Fix:

To fix the problem, I removed the 1st truncation call. This is okay, since request/response bodies are always truncated again in the 2nd call.

Before / after:

To showcase the issue, I used a simple request which consists of the letter "a" repeated for 10 KiB.

Before:

After: