Improve the variables passed in trigger-build
Improve the variables passed in trigger-build

Make the variable names consistent by following the
`TOP_UPSTREAM_SOURCE_*` pattern.

Signed-off-by: Rémy Coutable <4ea0184b9df19e0786dd00b28e6daa4d26baeb3e@rymai.me>

dreampet/gitlab,iiet/iiet-git,iiet/iiet-git,axilleas/gitlabhq,iiet/iiet-git,iiet/iiet-git,mmkassem/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,axilleas/gitlabhq,dreampet/gitlab