"Try it out" fails when webserver is hosting for multiple IRIS servers

[gjsjohnmurray]

1. Use a 2024.1+ installation, whose IRIS Portal url contains an extra segment by default, e.g. http://localhost/irislatest/csp/sys/... for an IRIS instance named IRISLATEST when installed.
2. Examine the http://localhost/irislatest/api/mgmnt/v1/%25SYS/spec/api/atelier API.
3. Expand one of the endpoints, for example GET /
4. Notice that the failure is caused by SwaggerUI omitting the /irislatest segment from the url it uses.