BUG/MINOR: mworker: fix typo in chroot error message

BUG/MINOR: mworker: fix typo in chroot error message

Since its introduction in 1.8 with commit 095ba4c24 ("MEDIUM: mworker:
replace systemd mode by master worker mode"), it says "cannot chroot1(...)"
which seems to be a leftover of a debug message. It could be backported but
probably nobody will notice.

(cherry picked from commit e34cf2801154eae542191120d5165a963d2cb98c)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 46317376f2f3be9c7e7df0c2b996716a5818fa77)
Signed-off-by: Willy Tarreau <w@1wt.eu>