This function call was previously used to generate mappings from
potential subjects (or SANs) to certificates within the TLS client
object. However, newer Go versions have deprecated this method, instead
building the mapping automatically based on present certificates at
request time. Because the corresponding client configuration field is
not used in Vault (NameToCertificate), it is safe to remove this call
and leave it nil.
See also: 67d894ee65
See also: https://pkg.go.dev/crypto/tls#Config.BuildNameToCertificate
Signed-off-by: Alexander Scheel <alex.scheel@hashicorp.com>