Forbid the use of outdated ciphers for HTTPS protocol on exporters

 Apparently the CBC cipher is considered vulnerable to LUCKY13 attack.

PMM is 2.15.1, deployed on Docker.

Suggested implementation:

Remove CBC ciphers from https://github.com/percona/exporter_shared/blob/master/server.go#L107

Update and then release all exporters which uses exporter_shared library.

}}{{CipherSuites: []uint16{
            tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
            tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
            tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
            tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
            tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
            tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
        },