Allow Group owners to delete user's SCIM and SAML identities via API

What does this MR do and why?

To try to close #423592 (closed) and #387971 (closed)

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Before	After

How to set up and validate locally

bash delete_scim_identity.sh 

{"message":"202 Accepted"}

cat delete_scim_identity.sh
curl --location --request DELETE "http://127.0.0.1:3000/api/v4/groups/33/scim/test_uid" \

\--header "PRIVATE-TOKEN: \<token\>"

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.