[backport v2.9] GitRepoRestrictions not defaulting the GitRepo

[rancherbot]

This is a backport issue for #3077, automatically created via GitHub Actions workflow initiated by @manno

Original issue body:

GitRepoRestriction resources can be used to default GitRepos and restrict their values.

Default values for GitRepo resources, configured through a GitRepoRestriction resource are not applied, although the restrictions remain functional.

• defaultServiceAccount
• defaultClientSecretName

See #3056

[mmartin24]

Tested as described in #3077 (comment).
QASE link: Fleet-153

Verified error in Rancher v2.9-023781e52103c45a9bbdf3cb47d60b9336321daa-head with fleet fleet:0.10.5 and then working when pointing to fleet image v0.10.6-rc.1:

• Before fix:

Gitreporestriction is empty in job container and allows gitrepo to be deployed even when service account does not set right permissions:

• After fix:

Gitreporestriction is not empty and prevents gitrepo from being successfully deployed when service accounts lacks proper permissions: