Change _CT_DATAVERSE_SITEURL to DATAVERSE_SITEURL

[pdurbin]

This is where _CT_DATAVERSE_SITEURL appears, currently:

docker/compose/demo/compose.yml
12: _CT_DATAVERSE_SITEURL: "https://demo.example.org"

doc/sphinx-guides/source/container/running/demo.rst
127:Please note that for a few environment variables (the ones that start with %ct in :download:microprofile-config.properties <../../../../../src/main/resources/META-INF/microprofile-config.properties>), you have to prepend _CT_ to make, for example, _CT_DATAVERSE_SITEURL. We are working on a fix for this in #10285.

It should be changed to just DATAVERSE_SITEURL, after testing it, of course.

For more context on why CT was needed, see this issue:

• In containers, can't set DATAVERSE_SITEURL using documented methods #10285

See also:

• Bug Report: deployment fails with NPE when MPC value is only available profiled payara/Payara#6549
• FISH-8317 - Microprofile Config NPE for profiled setting payara/Payara#6550