Fix timing issue in psync2 test. (#9159)
Fix timing issue in psync2 test. (#9159)

*** [err]: PSYNC2: total sum of full synchronizations is exactly 4 intests/integration/psync2.tcl
Expected 5 == 4 (context: type eval line 8 cmd {assert {$sum == 4}} proc::test)

Sometime the test got an unexpected full sync since a replica switch to master,
before the new master change propagated the new replid to all replicas,
a replica attempted to sync with it using a wrong replid and triggered a full resync.

Consider this scenario:
    1 slaveof 4 full resync
    0 slaveof 4 full resync
    2 slaveof 0 full resync
    3 slaveof 1 full resync

    1 slaveof no one, replid changed
    3 reconnect 1, did a partial resyn and got the new replid

    Before 2 inherits the new replid.
    3 slaveof 2
    3 try to do a partial resyn with 2.
    But their replication ids are inconsistent, so a full resync happens.

:) A special thank you for oran and helping me in this test case.

Co-authored-by: Oran Agra <4bc4982385244a2789f53ac695e2aa0ced00df6d@redislabs.com>
JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis