ci(enable-fork): set fork interval to 10 seconds

[Tang-Haojin]

This change can help us to capture the waveform of problem caused by hardware stuck. Besides, since we enlarged mmap memory, it may take much more time on fork() syscall. Enlarging the fork interval here also results better simulation speed in some circumstances.

[Tang-Haojin]

Some profiling evidences here. When I add -X 10, the CPU usage can reach 100% approximately.

[XiangShanRobot]

[Generated by IPC robot]
commit: 9357c6e

commit	astar	copy_and_run	coremark	gcc	gromacs	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
9357c6e	1.924	0.450	2.701	1.198	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.745	2.428	3.271

master branch:

commit	astar	copy_and_run	coremark	gcc	gromacs	lbm	linux	mcf	microbench	milc	namd	povray	wrf	xalancbmk
1eae6a3	1.924	0.450	2.701	1.198	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.745	2.428	3.271
f20002a	1.936	0.450	2.701	1.198	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.745	2.428	3.271
b2d1865	1.936	0.450	2.701	1.198	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.745	2.428	3.271
c1ebb15	1.936	0.450	2.701	1.199	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.755	2.429	3.271
b2e314e	1.936	0.450	2.701	1.199	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.755	2.429	3.271
5e0a22e	1.924	0.450	2.701	1.199	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.755	2.429	3.271
ca0aa83	1.924	0.450	2.701	1.199	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.755	2.429	3.271
b2564f6	1.936	0.450	2.701	1.199	2.812	2.465	2.404	0.914	1.394	1.626	3.424	2.755	2.429	3.271
cabb9f4	1.934	0.451	2.704	1.193	2.812	2.465	2.404	0.913	1.401	1.626	3.420	2.750	2.429	3.271