Make sure scheduler threads don't ACK the quiescence protocol CNF messages if they have an actor waiting to be run #2828

Job	Run time
Lint bash, docker, markdown, and yaml	1m 42s
Validate musl Docker image builds	21s
Validate GNU Docker image builds	32s
Validate GNU Docker release image builds	33s
Validate musl Docker release image builds	20s
Validate Windows Docker image builds	2m 11s
Validate Windows Docker release image builds	2m 57s
aarch64 Linux glibc	21m 14s
arm64 Apple Darwin	16m 1s
armhf Linux glibc	28m 13s
arm Linux glibc	28m 1s
riscv64 Linux glibc	21m 57s
Verify CHANGELOG is valid	10s
x86-64 Linux glibc	21m 59s
x86-64 Apple Darwin	27m 5s
x86-64 Windows MSVC	36m 47s
x86-64 Linux musl	23m 26s
use dtrace	20m 56s
use pool_memalign	25m 34s
use runtimestats	21m 32s
	5h 1m 31s

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