test/rpc: fix file handle leak in status fd reader

Use 'with' statement instead of manual open/read/close to
ensure the file is closed if read() raises an exception.

Assisted-by: Claude Code (claude-opus-4-6)
Signed-off-by: Adrian Reber <areber@redhat.com>

test/others/rpc/read.py

@@ -7,9 +7,8 @@
 
 import sys
 
-f = open(sys.argv[1])
-r = f.read(1)
-f.close()
+with open(sys.argv[1]) as f:
+    r = f.read(1)
 
 if r == '\0':
     sys.exit(0)