BACKPORT: sched/fair: Always trigger resched at the end of a protected period

Always trigger a resched after a protected period even if the entity is
still eligible. It can happen that an entity remains eligible at the end
of the protected period but must let an entity with a shorter slice to run
in order to keep its lag shorter than slice. This is particulalry true
with run to parity which tries to maximize the lag.

Bug: 438500731
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250708165630.1948751-7-vincent.guittot@linaro.org


[Trivial conflict in fair.c due to code differences from upstream.]
(cherry picked from commit 0b9ca2dc)
Signed-off-by: Qais Yousef <qyousef@google.com>
Change-Id: Ib616567f67c81f2945f3d141004614373b0c48f6