fix: resolve all Ruff linting errors

- Fix PLW2901: Use different variable name for stripped lines in loop
- Fix E721: Use 'is' instead of '==' for type comparisons
- Add noqa comments for intentional security warnings (S321, S507, S110, S603)

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

tests/test_e2e_full_stack.py

@@ -449,7 +449,7 @@ class TestFullInfrastructure:
 
         # Create SFTP client
         ssh = paramiko.SSHClient()
-        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
+        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())  # noqa: S507
 
         # Connect to SFTP server
         ssh.connect(