[9.18] fix: test: Limit X-Bloat header size to 100KB

Otherwise curl 8.13 rejects the line with:

    I:Check HTTP/1.1 keep-alive with truncated stream (21)
    curl: option --header: error encountered when reading a file
    curl: try 'curl --help' or 'curl --manual' for more information

Also, see https://github.com/curl/curl/pull/16572.

Closes #5249

Backport of MR !10319

Merge branch 'backport-5249-statschannel-limit-http-header-size-9.18' into 'bind-9.18'

See merge request isc-projects/bind9!10322

bin/tests/system/statschannel/tests.sh

@@ -591,7 +591,8 @@ i=0
 if [ -x "${CURL_NEXT}" ]; then
   # build input stream.
   printf 'X-Bloat: ' >header.in$n
-  while test $i -lt 5000; do
+  # curl 8.13 and newer rejects to read line larger than 100KB
+  while test $i -lt 1023; do
     printf '%s' "VGhlIG1vc3QgY29tbW9uIHJlYXNvbiBmb3IgYmxvYXRpbmcgaXMgaGF2aW5nIGEgbG90IG9mIGdhcyBpbiB5b3VyIGd1dC4gCg==" >>header.in$n
     i=$((i + 1))
   done