In the current scenario, if during startup, a node crashes after initiating gossip and before joining group0,
then it keeps floating in the gossiper forever because the raft based gossiper purging logic is only effective
once node joins group0. This orphan node hinders the successor node from same ip to join cluster since it collides
with it during gossiper shadow round.
This commit intends to fix this issue by adding a background thread which periodically checks for such orphan entries in
gossiper and removes them.
A test is also added in to verify this logic. This test fails without this background thread enabled, hence
verifying the behavior.
Fixes: scylladb/scylladb#20082Closesscylladb/scylladb#21600
(cherry picked from commit 6c90a25014)
Closesscylladb/scylladb#21822
f5bce45399