builder: use 'server' instead of 'url' for config

Mostly to be more in line with how things are called in all other
koji configuration files.

container/builder/osbuild-koji.conf

@@ -1,7 +1,7 @@
 [composer]
-url = https://composer/
+server = https://composer/
 ssl_cert = /share/worker-crt.pem, /share/worker-key.pem
 ssl_verify = /share/worker-ca.pem
 
 [koji]
-url = https://localhost:4343/kojihub/
+server = https://localhost:4343/kojihub/

plugins/builder/osbuild.py

@@ -221,14 +221,14 @@ class OSBuildImage(BaseTaskHandler):
 
         cfg = configparser.ConfigParser()
         cfg.read_dict({
-            "composer": {"url": DEFAULT_COMPOSER_URL},
-            "koji": {"url": DEFAULT_KOJIHUB_URL}
+            "composer": {"server": DEFAULT_COMPOSER_URL},
+            "koji": {"server": DEFAULT_KOJIHUB_URL}
         })
 
         cfg.read(DEFAULT_CONFIG_FILES)
 
-        self.composer_url = cfg["composer"]["url"]
-        self.koji_url = cfg["koji"]["url"]
+        self.composer_url = cfg["composer"]["server"]
+        self.koji_url = cfg["koji"]["server"]
         self.client = Client(self.composer_url)
 
         self.logger.debug("composer: %s", self.composer_url)

test/unit/test_builder.py

@@ -267,12 +267,12 @@ class TestBuilderPlugin(PluginTest):
 
             cfg = configparser.ConfigParser()
             cfg["composer"] = {
-                "url": composer_url,
+                "server": composer_url,
                 "ssl_cert": ssl_cert,
                 "ssl_verify": ssl_verify
             }
             cfg["koji"] = {
-                "url": koji_url
+                "server": koji_url
             }
 
             cfgfile = os.path.abspath(os.path.join(tmp, "ko.cfg"))