devshell: Do not add scripts/git-intercept to PATH

The use of scripts/git-intercept was introduced in commit 3266c327
(install/devshell: Introduce git intercept script due to fakeroot
issues) and later reverted in commit af27c81e (scripts: Make git
intercept global).

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>