GATEWAY_GRPC_ADDR, OCIS_GATEWAY_GRPC_ADDR, WEB_GATEWAY_GRPC_ADDR vs OCIS_REVA_GATEWAY

basically we should kill OCIS_GATEWAY_GRPC_ADDR.
The four env vars are used partly redundant, partly conflicting, partly unneded:
`GATEWAY_GRPC_ADDR` defines the bind address for the gateway service, a host and port or maybe a path when the `GATEWAY_GRPC_PROTOCOL=unix` for unix sockets. But it is never a service name. So:
- [ ] `OCIS_GATEWAY_GRPC_ADDR` should not be read by the gateway service. Deprecate the env var,
- [ ] `OCIS_GATEWAY_GRPC_ADDR` shoultd not be read by the storage-users service or overwritten with the more specific `STORAGE_USERS_GATEWAY_GRPC_ADDR`. The addr here is used by the trasbin commands to connect to the gateway. It can be an host:port address, a unix:/path/to/socket or a service name. currently defaults to ̀`127.0.0.1:9142`. It should be replaced with `OCIS_REVA_GATEWAY;STORAGE_USERS_REVA_GATEWAY` because it can be a service name.
- [ ] `WEB_GATEWAY_GRPC_ADDR` should be `OCIS_REVA_GATEWAY;WEB_REVA_GATEWAY` because it can be a service name as well as an address. it is used by the web service to initiate logo changes

Now that being said, the yaml tag for OCIS_REVA_GATEWAY is inconsistent as well:
service | yaml | env
-|-|-
shared | address | OCIS_REVA_GATEWAY
thumbnails | reva_gateway | OCIS_REVA_GATEWAY
webdav | reva_gateway | OCIS_REVA_GATEWAY
notifications | reva_gateway | OCIS_REVA_GATEWAY
collaboration | name | OCIS_REVA_GATEWAY;COLLABORATION_CS3API_GATEWAY_NAME
clientlog | reva_gateway | OCIS_REVA_GATEWAY;CLIENTLOG_REVA_GATEWAY
activitylog | reva_gateway | OCIS_REVA_GATEWAY
storage-users | gateway_addr | OCIS_GATEWAY_GRPC_ADDR;STORAGE_USERS_GATEWAY_GRPC_ADDR
search | address | OCIS_REVA_GATEWAY
userlog | reva_gateway | OCIS_REVA_GATEWAY
web | gateway_addr | WEB_GATEWAY_GRPC_ADDR

for yaml I think we have no override mechanic, right?