fix: account header username

[UnicornChance]

Description

Account Header was broken and now it isn't.

Before: The welcome-page-script would attempt to get the users givenName and familyName, which it would do successfully, and then it uses this reduce function to combine those two names into a single name, with the caveat that it has to have a specific format specified in the messages_en.properties file. That value was not set correctly for the reduce function to use the parameters.

Testing:

1. Setup uds-core with keycloak/authservice
2. create admin user
3. go to sso.uds.dev and register a user
4. in admin console verify that users email address ( should now be able to get to the users account )
5. in the top right of the user account site, see the 'Full Name' beside the Sign Out button ( this should be the users full name )
6. with that local cluster still running, go to this repo and branch and run uds run dev-theme to copy in the new theme for keycloak
7. refreshing the users account should now show your users full name instead of the static text Full Name

...

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

Checklist before merging

• Test, docs, adr added or updated as needed
• Contributor Guide Steps(https://github.com/defenseunicorns/uds-template-capability/blob/main/CONTRIBUTING.md#submitting-a-pull-request) followed

[mjnagel]

Took a while to get to this to test, LGTM!