purpose of task is to solve the design issue on hr expense banner
when there is horizontal scrolling on tree view then the banner on
top will not adapt it so there is empty space at last.
So in this commit, Fix the position of the expense header so it should
not scroll with the tree.
closesodoo/odoo#60105
Taskid: 2336309
X-original-commit: 7ba0bc47d1404d5ac4bbf8cb5dcca7937558bd1a
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>