Add API support for admin setting to 'bypass placeholder confirmation'
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This issue was created from the suggestion https://gitlab.com/gitlab-org/gitlab/-/merge_requests/188810#note_2493727674.
### About
We should add API support for the new `allow_enterprise_bypass_placeholder_confirmation` boolean application setting being added in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/188810 as part of https://gitlab.com/gitlab-org/gitlab/-/issues/534329.
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