fix failing cluster tests (#9695)
fix failing cluster tests (#9695)

When stopping an instance in the cluster tests, disable appendonly first, so that SIGTERM won't be ignored.

Recently in #9679 i change the test infra to use SIGSEGV to kill servers that refuse
the SIGTERM rather than do SIGKILL directly.

This surfaced an issue that i've added in #7725 which changed SIGKILL to SIGTERM (to resolve valgrind issues).
So the current situation in the past months was that sometimes servers refused the
SIGTERM and waited 10 seconds for the SIGKILL, and this commit resolves that (faster termination).
ofirluzon/redis,yossigo/redis,charsyam/redis,yossigo/redis,ofirluzon/redis,oranagra/redis,antirez/redis,soloestoy/redis,soloestoy/redis,oranagra/redis,antirez/redis,soloestoy/redis,ofirluzon/redis,oranagra/redis,soloestoy/redis,PKRoma/redis,ofirluzon/redis,soloestoy/redis,charsyam/redis,neomantra/redis,antirez/redis,charsyam/redis,yossigo/redis,ofirluzon/redis,oranagra/redis,charsyam/redis,yossigo/redis,PKRoma/redis,neomantra/redis,neomantra/redis,PKRoma/redis,neomantra/redis,antirez/redis,yossigo/redis,oranagra/redis,neomantra/redis,PKRoma/redis,charsyam/redis,PKRoma/redis