Revert "[rpc] Deprecate estimatefee RPC" (D1920)
This reverts PARTIALLY reverts commit 49ff27fedd365dcf5f7639fd2bda5dfc3cc58f51
The instrumentation for enabling deprecated RPCs is left in place for future use.
However, estimatefee should not be deprecated in a point release. It's also possible
that it should not be deprecated at all since we removed estimatesmartefee which
core deprecated this in favor of.
Depends on D2013