Enable ff_require_saml_auth_to_approve by default

What does this MR do and why?

Enables ff_require_saml_auth_to_approve feature flag to default true, so we can release the accompanying release post MR for this feature.

• Set feature flag ff_require_saml_auth_to_approve to default enabled Flag was set to 100% enabled on gprd on 2023-11-29 21:45 UTC by @dblessing and is still set. Evidence:

  • #431714 (comment 1722976173)
  • https://gitlab.slack.com/archives/C101F3796/p1704966046769529

• Refs: #431714

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