Deflake Psync established within grace period (#2743)

increased the wait time to a total of 10 seconds where we check the log
for `Done loading RDB` message

Fixes #2694

CI run (100 times):
https://github.com/roshkhatri/valkey/actions/runs/18576201712/job/52961907806

Signed-off-by: Roshan Khatri <[email protected]>
(cherry picked from commit 898172b)
Signed-off-by: cherukum-amazon <[email protected]>

Author: roshkhatri

tests/integration/dual-channel-replication.tcl

@@ -692,7 +692,7 @@ start_server {tags {"dual-channel-replication external:skip"}} {
             # 5. Replica resumes operation.
             # Expected outcome: Primary maintains RDB channel until replica establishes PSYNC connection.
             $replica replicaof $primary_host $primary_port
-            wait_for_log_messages 0 {"*Done loading RDB*"} $loglines 2000 1
+            wait_for_log_messages 0 {"*Done loading RDB*"} $loglines 2000 5
             pause_process $replica_pid
             wait_and_resume_process -1
             wait_for_condition 50 100 {