Fix file.managed error prefix and redact basic-auth in source_hash errors

Forward-port from 3008.x commit 3fafbbe to master:

- salt/states/file.py: prefix the early `_error()` return in
  `file.managed` with "Unable to manage file:" so callers and tests can
  reliably distinguish the manage-file failure path from other state
  errors. Restores the assertion checked by
  tests/pytests/functional/states/file/test_managed.py::test_issue_60203,
  which is failing across every functional-zeromq-3 chunk on master.

- salt/modules/file.py: route the `source_hash` value through
  `salt.utils.url.redact_http_basic_auth()` in both the "format is
  invalid" and "Source hash file not found" error paths of
  `get_source_sum()` so HTTP basic-auth credentials are not leaked into
  state comments or logs when the source hash URI is malformed or
  unreachable.

Author: dwoz

changelog/69402.fixed.md

@@ -0,0 +1,4 @@
+Prefix ``file.managed`` error comments with ``Unable to manage file:`` and
+redact HTTP basic-auth credentials from ``Source hash`` error messages in
+``salt.modules.file.get_source_sum`` so they are not leaked in state output
+or logs.