Remove unused declarations

[milleruntime]

Second commit is questionable whether to remove a new unused parameter before released to API in 2.0. Other removals should all be internal.

[mikewalch]

I would just be very careful with API

[milleruntime]

Reverted the commit that touched the new API. Then reran the code inspection to see what else is now unused.

[milleruntime]

@mikewalch or @keith-turner you guys OK with the rest of the changes?

[milleruntime]

@ctubbsii thanks for taking a look at this. This was more of an experiment using Intellij Run Inspection by name but it became too cumbersome with our API and pluggable interfaces. I plan on using a more focused approach for removing unused code next time.

[ctubbsii]

@milleruntime I thought this worked out fine. It caught some stuff we maybe didn't want removed... but I think we caught all those in the reviews. Even if we didn't, the risk was minimal, since none of it touched the public API.

[ctubbsii]

Eventually, all our "internal pluggable" stuff should be in declared SPI packages, to make it easier to ensure stability. We're still stuck with the historical stuff for now, though.