Fix free-standing transaction lookup with module-based shards

Fix free-standing transaction lookup with module-based shards

When we have a combination of tell-based protocol with module-based
shards, the frontend will use the cookie within LocalHistoryIdentifier,
making it potentially non-zero.

The backend tracks free-standing transactions under a local history,
which has cookie set to zero, hence it will not match when we attempt
to look it up for the purposes commit/abort/purge -- leading to
mismatched leader state for these transactions.

Change-Id: Ic4a493d0728b8de288a779d8c97a157584dc76bb
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>