fix: align storage metadata GPRC bind port with other variable names

Currently STORAGE_METADATA_GRPC_PROVIDER_ADDR environment variable used as the way to set the GRPC bind port for the service.  All other services use the format <SERVICE_NAME>_GRPC_ADDR for GRPC, and <SERVICE_NAME>_HTTP_ADDR for HTTP.  This change brings it in line with the others, as it's confusing why this one is different.

storage/pkg/config/config.go

@@ -1234,7 +1234,7 @@ func structMappings(cfg *Config) []shared.EnvBinding {
 			Destination: &cfg.Reva.StorageMetadata.GRPCNetwork,
 		},
 		{
-			EnvVars:     []string{"STORAGE_METADATA_GRPC_PROVIDER_ADDR"},
+			EnvVars:     []string{"STORAGE_METADATA_GRPC_ADDR"},
 			Destination: &cfg.Reva.StorageMetadata.GRPCAddr,
 		},
 		{