storage: pick up fix for Raft uncommitted entry size tracking

The tracking of the uncommitted portion of the log had a bug where
it wasn't releasing everything as it should've. As a result, over
time, all proposals would be dropped. We're hitting this way earlier
in our import tests, which propose large proposals. As an intentional
implementation detail, a proposal that itself exceeds the max
uncommitted log size is allowed only if the uncommitted log is empty.
Due to the leak, we weren't ever hitting this case and so AddSSTable
commands were often dropped indefinitely.

Fixes #31184.
Fixes #28693.
Fixes #31642.

Optimistically:
Fixes #31675.
Fixes #31654.
Fixes #31446.

Release note: None