Fixed reduce_option=concat for auto_transformer and deberta

[tgaddair]

Also adds @slow tests for the reduce option and replaces monkeypatching with mocks.

[geoffreyangus]

Nice! Quick question– is there a functional difference between using PyTest's monkeypatch vs unittest's mock? Or is it just preference/convention

[tgaddair]

@geoffreyangus my concern with using monkeypatch here is that I don't believe it will "undo" itself when the fixture exits. The way it was implemented, it appears it will carry that patch through to any subsequent tests, which would be bad. The mocking here is in a context manager that will undo the mock when the context manager exits, which is what you would want.

[github-actions]

Unit Test Results

  6 files  ±       0    6 suites  ±0   21m 34s ⏱️ - 23m 30s
12 tests  - 2 474  10 ✔️  - 2 467    2 💤  -   7  0 ❌ ±0 
60 runs   - 4 924  48 ✔️  - 4 914  12 💤  - 10  0 ❌ ±0 

Results for commit b84cf2f. ± Comparison against base commit 25cc729.