Fix replication on expired key test timing issue, give it more chances (

#11548)

In replica, the key expired before master's `INCR` was arrived, so INCR
creates a new key in the replica and the test failed.
```
*** [err]: Replication of an expired key does not delete the expired key in tests/integration/replication-4.tcl
Expected '0' to be equal to '1' (context: type eval line 13 cmd {assert_equal 0 [$slave exists k]} proc ::test)
```

This test is very likely to do a false positive if the `wait_for_ofs_sync`
takes longer than the expiration time, so give it a few more chances.

The test was introduced in #9572.

tests/integration/replication-4.tcl

@@ -122,19 +122,35 @@ start_server {tags {"repl external:skip"}} {
         }
 
         test {Replication of an expired key does not delete the expired key} {
+            # This test is very likely to do a false positive if the wait_for_ofs_sync
+            # takes longer than the expiration time, so give it a few more chances.
+            # Go with 5 retries of increasing timeout, i.e. start with 500ms, then go
+            # to 1000ms, 2000ms, 4000ms, 8000ms.
+            set px_ms 500
+            for {set i 0} {$i < 5} {incr i} {
+
+            wait_for_ofs_sync $master $slave
             $master debug set-active-expire 0
-            $master set k 1 ex 1
+            $master set k 1 px $px_ms
             wait_for_ofs_sync $master $slave
             exec kill -SIGSTOP [srv 0 pid]
             $master incr k
-            after 1001
+            after [expr $px_ms + 1]
             # Stopping the replica for one second to makes sure the INCR arrives
             # to the replica after the key is logically expired.
             exec kill -SIGCONT [srv 0 pid]
             wait_for_ofs_sync $master $slave
             # Check that k is logically expired but is present in the replica.
-            assert_equal 0 [$slave exists k]
-            $slave debug object k ; # Raises exception if k is gone.
+            set res [$slave exists k]
+            set errcode [catch {$slave debug object k} err] ; # Raises exception if k is gone.
+            if {$res == 0 && $errcode == 0} { break }
+            set px_ms [expr $px_ms * 2]
+
+            } ;# for
+
+            if {$::verbose} { puts "Replication of an expired key does not delete the expired key test attempts: $i" }
+            assert_equal $res 0
+            assert_equal $errcode 0
         }
     }
 }