tsget: remove call of WWW::Curl::Easy::global_cleanup

This function is undocumented, but similarly named functions (such as
'curl_global_cleanup') are documented as internals that should not be
called by scripts.

Fixes #3765

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3769)