Revert "nm-device: prefer manually configured addresses to automatic"

This commit does not seem correct. The enum was moved with the declared
intent to make manual IP configuration preferred. But the code comment
in L3ConfigDataType and all the code there work under the assumption
that higher (numerical) values mean more important. So the patch
actually made manual the least important method.

I don't necessarily doubt that this fixes seemingly a scenario, but then
it does the wrong fix. If the priorities are not honored correctly (or
inverted), then the fix must address that, and not reorder some
priorities. In particular, when most of the code claims to work the
other way around.

Revert this commit. If this breaks something again, then we can
re-investigate.

There also appears to be a CI test for this [1]. Let's see how/whether it
regresses.

[1] NetworkManager-ci@9cd1b24c

This reverts commit af1903fe.
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