Fix TransformerBridge backward hook cleanup

[SamuelePunzo]

Fix TransformerBridge backward-hook cleanup so temporary backward hooks do not leak after context exit.

HookPoint.remove_hooks() defaults to forward-only cleanup, and TransformerBridge was calling it without an explicit direction in several cleanup paths. That
meant non-permanent backward hooks could remain attached after with model.hooks(...) exited, and reset_hooks() on bridge components could also miss backward
hooks.

This change:

• cleans up both directions in generalized component hook removal
• cleans up the specific direction that was added in TransformerBridge.hooks(...)
• cleans up the specific direction that was added in TransformerBridge.run_with_hooks(...)
• preserves unrelated backward hooks during run_with_cache(...) teardown by cleaning up only the forward cache hooks it adds
• adds regression tests for backward-hook cleanup on context exit, reset_hooks(), and run_with_cache(...)

This fixes the bug reported in the linked issue. No additional dependencies are required.

Fixes #1323

Type of change

• Bug fix (non-breaking change which fixes an issue)

Screenshots

Not applicable.

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have not rewritten tests relating to key interfaces which would affect backward compatibility