Extra savers in only-combining mode for superrun

[dachengx]

Describe the bug

After replacing

strax/tests/test_superruns.py

Lines 128 to 129 in c83050b

	assert len(components.loaders) == 1
	assert "peak_classification" in components.loaders

to

assert len(components.loaders) == 1
assert len(components.savers) == 1
assert "peak_classification" in components.loaders
assert "peak_classification" in components.savers

you will fond that the components.savers is not only for "peak_classification". This is not expected because the _combining_subruns = True mode only combine the input target.

Expected behavior

components.savers should be only for "peak_classification".

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Versions
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