deploy/zyxel_gs1900 - remove debugging and unnecessary console output

Remove left over test code permanently setting the uploaded cert password
to "password" an make sure to send the upload stdout and stderr to
/dev/null since we have no need for it and the text may confuse end
users running acme.sh.

deploy/zyxel_gs1900.sh

@@ -239,7 +239,6 @@ _zyxel_gs1900_upload_certificate() {
   # Generate a PKCS12 certificate with a temporary password since the web interface
   # requires a password be present. Then upload that certificate.
   temp_cert_password=$(head /dev/urandom | tr -dc 'A-Za-z0-9' | head -c 64)
-  temp_cert_password="password"
   _secure_debug2 "temp_cert_password" "$temp_cert_password"
 
   temp_pkcs12="$(_mktemp)"
@@ -295,7 +294,7 @@ _zyxel_gs1900_upload_certificate() {
   # to return a consistent body return - so we cannot inspect the result of this
   # upload to determine success. We will need to re-query the certificates page
   # and compare the validity dates to try and identify if they have changed.
-  _post "${upload_post_request}" "${_zyxel_switch_base_uri}/cgi-bin/httpuploadcert.cgi" '' "POST" "multipart/form-data; boundary=${upload_post_boundary}" '1'
+  _post "${upload_post_request}" "${_zyxel_switch_base_uri}/cgi-bin/httpuploadcert.cgi" '' "POST" "multipart/form-data; boundary=${upload_post_boundary}" '1' >/dev/null 2>&1
   rm "${upload_post_request}"
 
   # Pause for a few seconds to give the switch a chance to process the certificate