Hard-coded ciphersuite list incompatible with mariadb 10.1 on debian stretch

[kormat]

Currently there's a hard-coded list of accepted ciphersuites:

orchestrator/go/ssl/ssl.go

Lines 19 to 30 in df41873

	var cipherSuites = []uint16{
	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
	tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
	tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
	tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
	tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
	tls.TLS_RSA_WITH_AES_128_CBC_SHA,
	tls.TLS_RSA_WITH_AES_256_CBC_SHA,
	}

This list hasn't been updated in 5 years. It also happens to be incompatible with Mariadb 10.1 on debian stretch:

2021-02-02 09:23:30 ERROR ReadTopologyInstance(HOSTNAME:3306) show global status like 'Uptime': remote error: tls: handshake failure back.