server : remove CPPHTTPLIB_NO_EXCEPTIONS define (#11622)
This commit removes the CPPHTTPLIB_NO_EXCEPTIONS define from the server
code.
The motivation for this is that when using a debug build the server
would crash when an exception was throws and terminate the server
process, as it was unhandled. When CPPHTTPLIB_NO_EXCEPTIONS is set
cpp_httplib will not call the exception handler, which would normally
return a 500 error to the client. This caused tests to fail when using
a debug build.
Fixes: https://github.com/ggerganov/llama.cpp/issues/11613
