The test provides an invalid username, but no ':' with password, so that
the curl tool tries to read the password from stdin. That makes the test
hang, also in CI.
The check for invalid characters is happening when the CURLOPT_USERPWD
is applied to the URL, so when the transfer is started. Maybe the check
should happen also in setopt already.
The test hangs because tool_paramhlp.c:548 `checkpasswd()` does not see
a ':' and tries to read the password from stdin.
Fix: add a ':' in the tests invalid user setting, so that the read does
not happen.
Follow-up to ecaa344a7aCloses#22264
