re-use transport and set stronger backwards compatible Ciphers (#19565)

This PR fixes a few things

- FIPS support for missing for remote transports, causing
  MinIO could end up using non-FIPS Ciphers in FIPS mode

- Avoids too many transports, they all do the same thing
  to make connection pooling work properly re-use them.

- globalTCPOptions must be set before setting transport
  to make sure the client conn deadlines are honored properly.

- GCS warm tier must re-use our transport

- Re-enable trailing headers support.

cmd/config-current.go

@@ -678,7 +678,7 @@ func applyDynamicConfigForSubSys(ctx context.Context, objAPI ObjectLayer, s conf
 			}
 		}
 	case config.SubnetSubSys:
-		subnetConfig, err := subnet.LookupConfig(s[config.SubnetSubSys][config.Default], globalProxyTransport)
+		subnetConfig, err := subnet.LookupConfig(s[config.SubnetSubSys][config.Default], globalRemoteTargetTransport)
 		if err != nil {
 			configLogIf(ctx, fmt.Errorf("Unable to parse subnet configuration: %w", err))
 		} else {