Fix all flake8 warnings from newer flake8-bugbear and flake8-comprehensions

Address warnings introduced by flake8-bugbear 24.12.12 and
flake8-comprehensions 3.16.0:

- C408: Replace dict()/list() calls with literal {} and []
- C413: Remove unnecessary list() around sorted()
- C414: Remove unnecessary list() inside sorted()
- C419: Suppress intentional list comprehension in all() (noqa)
- B001: Replace bare except with except Exception
- B006: Replace mutable default arguments with None
- B010: Replace setattr() with direct attribute assignment
- B017: Use RuntimeError instead of Exception in tests
- B019: Suppress lru_cache on methods for long-lived objects (noqa)
- B033: Remove duplicate item in set literal

Change-Id: If4693d3e946200bbc22f689f7b94da604addcb80
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/566321
Tested-by: Carlos Fernandez <carlosfsanz@meta.com>
Commit-Queue: Carlos Fernandez <carlosfsanz@meta.com>
Reviewed-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>

ssh.py

@@ -149,7 +149,7 @@ class ProxyManager:
         while True:
             try:
                 procs.pop(0)
-            except:  # noqa: E722
+            except IndexError:
                 break
 
     def close(self):