remap_reload.test.py: fix override warnings (#12640)

remap_reload.test.py updates the remap.config file and issues a
`traffic_ctl config reload` to dynamically integrate those changes into
the running ATS process. Before this patch, this was done via creating a
new tr.Disk.File() object and writing to it. But this resulted in
warnings for overriding the already existing remap.config Disk.File from
the setup of the ATS process in the first place. This transitions the
test to modify the file via a Setup function instead. This achieves the
same result without alarming the autest framework about the conflicting
Disk.File object.

This patch cleans up these warnings:

```
╰─➤  ./autest.sh --sandbox /tmp/sb --clean=none -f remap_reload
Running Test remap_reload:Warning: Overriding file object /tmp/sb/remap_reload/ts/config/remap.config
Warning: Overriding file object /tmp/sb/remap_reload/ts/config/remap.config
........ Passed
``

Author: bneradt

tests/gold_tests/remap/remap_reload.test.py

@@ -15,6 +15,20 @@
 #  limitations under the License.
 import os
 
+
+def update_remap_config(path: str, lines: list) -> None:
+    """Update the remap.config file.
+
+    This is used to update the config file between test runs without
+    triggering framework warnings about overriding file objects.
+
+    :param path: The path to the remap.config file.
+    :param lines: The list of lines to write to the file.
+    """
+    with open(path, 'w') as f:
+        f.write('\n'.join(lines) + '\n')
+
+
 Test.Summary = '''
 Test remap reloading
 '''
@@ -54,15 +68,15 @@
 tr.AddVerifierClientProcess("client", replay_file_1, http_ports=[tm.Variables.port])
 
 tr = Test.AddTestRun("Change remap.config to have only two lines")
-tr.Processes.Default.Env = tm.Env
-tr.Processes.Default.Command = 'echo "Change remap.config, two lines"'
-tr.Disk.File(remap_cfg_path).WriteOn("")
-tr.Disk.File(
-    remap_cfg_path, typename="ats:config").AddLines(
-        [
+p = tr.Processes.Default
+p.Env = tm.Env
+p.Command = 'echo "Change remap.config, two lines"'
+p.Setup.Lambda(
+    lambda: update_remap_config(
+        remap_cfg_path, [
             f"map http://alpha.ex http://alpha.ex:{pv_port}",
             f"map http://bravo.ex http://bravo.ex:{pv_port}",
-        ])
+        ]))
 
 tr = Test.AddTestRun("remap_config reload, fails")
 tr.Processes.Default.Env = tm.Env
@@ -75,18 +89,18 @@
 tr.Processes.Default.StartBefore(await_config_reload)
 
 tr = Test.AddTestRun("Change remap.config to have more than three lines")
-tr.Processes.Default.Env = tm.Env
-tr.Processes.Default.Command = 'echo "Change remap.config, more than three lines"'
-tr.Disk.File(remap_cfg_path).WriteOn("")
-tr.Disk.File(
-    remap_cfg_path, typename="ats:config").AddLines(
-        [
+p = tr.Processes.Default
+p.Env = tm.Env
+p.Command = 'echo "Change remap.config, more than three lines"'
+p.Setup.Lambda(
+    lambda: update_remap_config(
+        remap_cfg_path, [
             f"map http://echo.ex http://echo.ex:{pv_port}",
             f"map http://foxtrot.ex http://foxtrot.ex:{pv_port}",
             f"map http://golf.ex http://golf.ex:{pv_port}",
             f"map http://hotel.ex http://hotel.ex:{pv_port}",
             f"map http://india.ex http://india.ex:{pv_port}",
-        ])
+        ]))
 
 tr = Test.AddTestRun("remap_config reload, succeeds")
 tr.Processes.Default.Env = tm.Env