This reverts commit 19ead44.

Reason: late evaluation of arguments causes errors in mypy;
also this seems to be the more common (as per SA docs) and more readable
method compared to lambdas.

Downside #1: a typo in the string value won't be caught by lint tools.
Downside galaxyproject#2: if there's a sufficiently complex statement, it will be
hard to read if it's all on one line;

primaryjoin = "and_(HistoryDatasetAssociation.history_id == History.id, not_(HistoryDatasetAssociation.deleted), HistoryDatasetAssociation.visible)"

splitting across lines will require surrounding each line with quotes:

primaryjoin = (
   "and_("
   "HistoryDatasetAssociation.history_id == History.id,"
   "not_(HistoryDatasetAssociation.deleted),"
   "HistoryDatasetAssociation.visible,"
    ")"
)

Still, I think it's better than the alternative (lambda + multiple type-ignores
after each line:

primaryjoin = lambda(
   and_(
        HistoryDatasetAssociation.history_id == History.id,  # type:ignore[has-type, arg-type]
        not_(HistoryDatasetAssociation.deleted),  # type:ignore[has-type, arg-type]
        HistoryDatasetAssociation.visible,  # type:ignore[has-type, arg-type]
    )
)

* Rename `delta` to `eps` for float-based assertions

* Fix tests