Machine:remove field name in config(#6892)

Because our machine name now is the key value of the machine config
dict. And the machine config value will been overwritten by it when the
config is loaded. We can remove the field `name` from the config.

dvc/config_schema.py

@@ -241,7 +241,6 @@ SCHEMA = {
                 Lower, Choices("us-west", "us-east", "eu-west", "eu-north")
             ),
             "image": str,
-            "name": str,
             "spot": Bool,
             "spot_price": Coerce(float),
             "instance_hdd_size": Coerce(int),

tests/func/machine/test_machine_config.py

@@ -16,7 +16,6 @@ from .conftest import BASIC_CONFIG
     [
         ("region", "us-west"),
         ("image", "iterative-cml"),
-        ("name", "iterative_test"),
         ("spot", "True"),
         ("spot_price", "1.2345"),
         ("spot_price", "12345"),
@@ -75,7 +74,6 @@ FULL_CONFIG_TEXT = textwrap.dedent(
             cloud = aws
             region = us-west
             image = iterative-cml
-            name = iterative_test
             spot = True
             spot_price = 1.2345
             instance_hdd_size = 10