fix: support custom hosts for SCM auth

[JessicaJHee]

Description

Fixes bug by reading configured host from integrations.<providerId>.host instead of calling ScmAuth.createDefaultApiFactory(), which only supports default provider hosts (falls back to default URL if host option is not provided).

Which issue(s) does this PR fix

• Fixes RHDHBUGS-1028

PR acceptance criteria

Please make sure that the following steps are complete:

• GitHub Actions are completed and successful
• Unit Tests are updated and passing
• E2E Tests are updated and passing
• Documentation is updated if necessary (requirement for new features)
• Add a screenshot if the change is UX/UI related

How to test changes / Special notes to the reviewer

1. Configure GitLab Enterprise integration with self-hosted/ enterprise host in app-config

integrations:
  gitlab:
    - host: gitlab.company.com

2. Attempt to use a software template with:

          ui:field: RepoUrlPicker
          ui:options:
            allowedHosts:
              - gitlab.company.com

3. Ensure No auth provider available for 'https://gitlab.company.com' error does not appear

[github-actions]

The image is available at:

• quay.io/rhdh-community/rhdh:pr-3309 or
• quay.io/rhdh-community/rhdh:pr-3309-c6162a4b

[albarbaro]

/lgtm
/approve

[albarbaro]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: albarbaro

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• OWNERS [albarbaro]

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[kim-tsao]

/cherrypick release-1.7

[openshift-cherrypick-robot]

@kim-tsao: new pull request created: #3530

In response to this:

/cherrypick release-1.7

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