GATEWAY_GRPC_ADDR, OCIS_GATEWAY_GRPC_ADDR, WEB_GATEWAY_GRPC_ADDR vs OCIS_REVA_GATEWAY

[butonic]

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?

[dragonchaser]

related to #8259