We can pass bound_service_account_names with a comma separated list of
service accounts. Let's do this instead of remapping new values.
Earlier, we thought a single service account could be added per Vault
role and we were using other variables like
`VAULT_AUTH_KUBERNETES_ROOK_OPERATOR_ROLE` that we were remapping to
`VAULT_AUTH_KUBERNETES_ROLE` internal for the API calls to Vault.
Signed-off-by: Sébastien Han <seb@redhat.com>