Replace eu-west-1 with system.local data_center value

[Gor027]

The create_cloud_config function generates files config_data.yaml and config_path.yaml. The files were created with the hardcoded datacenter name eu-west-1 which is now replaced by fetching the real datacenter name from the node's system.local table.

[fruch]

@Gor027 you tested it with the test in both java and python drivers ?

[Gor027]

@Gor027 you tested it with the test in both java and python drivers ?

I have tested it with the Rust driver: https://github.com/scylladb/scylla-rust-driver/blob/main/examples/cloud.rs

The single-DC cluster was created as follows:

ccm create ccm_12 -i 127.0.1. -n 1 --scylla -v release:4.6.9
ccm start  --sni-proxy --sni-port 7777

The JSON output that ccm start prints should include the fetched datacenter parameter:

...
 [json]
---------------------------------------------------------------------------------------------------------------------
 {"host_id": "5ca930d1-e438-4f39-b9f9-358da6fb07be", "broadcast_address": "127.0.1.1", "data_center": "datacenter1"}
...

The generated config_data.yaml was used in the cloud test mentioned above.