http_client.c: fix tracing error response message bodies #1526

Job	Run time
run-checker (no-cmp)	5m 6s
run-checker (no-cms)	5m 17s
run-checker (no-dgram)	5m 1s
run-checker (no-dh)	5m 26s
run-checker (no-dtls)	5m 15s
run-checker (no-ec)	4m 40s
run-checker (no-ecx)	5m 15s
run-checker (no-http)	5m 9s
run-checker (no-legacy)	5m 20s
run-checker (no-sock)	4m 44s
run-checker (enable-ssl-trace)	5m 19s
run-checker (no-stdio)	2m 16s
run-checker (no-threads)	5m 9s
run-checker (no-thread-pool)	5m 25s
run-checker (no-default-thread-pool)	5m 28s
run-checker (no-tls)	4m 51s
run-checker (no-tls1_2)	5m 21s
run-checker (no-tls1_3)	4m 56s
run-checker (enable-trace enable-fips)	5m 51s
run-checker (no-ui)	5m 24s
run-checker (no-quic)	5m 14s
	1h 46m 27s

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