buildhistory: Move WEBOS_BOM_data.pkl to TMPDIR

:Release Notes:
WEBOS_BOM_data.pkl in buildhistory repo was causing bigger diffs
which aren't easy to read.

:Detailed Notes:
Release notes script is using WEBOS_BOM_data.pkl file from build
artifacts so we don't need to store this in buildhistory repository.
Jenkins jobs need to be updated to preserve this file from new location.

:Testing Performed:
WEBOS_BOM_data.pkl is no longer commited in buildhistory repository
with each build.

:QA Notes:
No change in image

:Issues Addressed:
[GF-2545] Enable retention of buildhistory

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Change-Id: Ifeff1d86fa3634d489c66ba4d5c5fadfaf5bfda5
Reviewed-on: https://g2g.palm.com/2863
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>