Revert PRs 1534 and 1586

[danlaine]

Why this should be merged

There's a bug in #1534. #1586 is built atop 1534.

The iterator of linkedhashmap, used by the node cache, says:

// Assumes the underlying LinkedHashmap is not modified while
// the iterator is in use, except to delete elements that
// have already been iterated over.

but in onEvictCache's Flush method, called on Close, we do exactly this. Namely, when we call c.onEviction, we call removeOldest on the cache which modifies the linkedHashmap.

Will make a subsequent PR to revert #1534. #1586 was built atop #1534.

How this works

Revert #1534 and #1586

How this was tested

N/A

[danlaine]

converted to a draft while we consider other fixes

[danlaine]

Closing in favor of #1589