sched: Update MAINTAINERS and CREDITS

Thank you Daniel for having been our friend!

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20240708075752.GF11386@noisy.programming.kicks-ass.net