Drop the redundant 'X as X' import aliases

The 'import X as X' form is the explicit-re-export idiom for mypy's
no_implicit_reexport, which this repo doesn't enable (commented out in
mypy.ini), so plain imports re-export just as well. ContextResourceUsage
is the one name not otherwise used in the module, so it keeps a noqa to
mark the intentional re-export for ruff.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JFbRtswu7rsHrttJFauUUb

synapse/logging/context.py

@@ -53,12 +53,13 @@ from twisted.python.threadpool import ThreadPool
 from synapse.logging.loggers import ExplicitlyConfiguredLogger
 from synapse.synapse_rust.logcontext import (
     DEBUG_LOGGER_NAME,
-    SENTINEL_CONTEXT as SENTINEL_CONTEXT,
-    ContextResourceUsage as ContextResourceUsage,
-    LoggingContext as LoggingContext,
-    _Sentinel as _Sentinel,
-    current_context as current_context,
-    set_current_context as set_current_context,
+    SENTINEL_CONTEXT,
+    # Not used in this module, but re-exported: callers import it from here.
+    ContextResourceUsage,  # noqa: F401
+    LoggingContext,
+    _Sentinel,
+    current_context,
+    set_current_context,
 )
 from synapse.util.stringutils import random_string_insecure_fast