Fix 'RESTORE can set LFU' test (#13896)

When the `restore foo 0 $encoded freq 100` command and `set freq [r
object freq foo]` run in different minute timestamps (i.e., when
server.unixtime/60 changes between these operations), the assertion may
fail due to the LFU decay.

This PR updates the “RESTORE can set LFU” test to verify the actual freq
value based on minute timestamps.

---------

Co-authored-by: debing.sun <debing.sun@redis.com>

tests/unit/dump.tcl

@@ -66,8 +66,24 @@ start_server {tags {"dump"}} {
         r del foo
         r config set maxmemory-policy allkeys-lfu
         r restore foo 0 $encoded freq 100
+
+        # We need to determine whether the `object` operation happens within the same minute or crosses into a new one
+        # This will help us verify if the freq remains 100 or decays due to a minute transition
+        set start [clock format [clock seconds] -format %M]
         set freq [r object freq foo]
+        set end [clock format [clock seconds] -format %M]
+
+        if { $start == $end } {
+            # If the minutes haven't changed (i.e., the restore and object happened within the same minute),
+            # the freq should remain 100 as no decay has occurred yet.
             assert {$freq == 100}
+        } else {
+            # If the object operation crosses into a new minute, freq may have already decayed by 1 (99),
+            # or it may still be 100 if the minute update hasn't been applied yet when the operation is performed.
+            # The decay might only take effect after the operation completes and the minute is updated.
+            assert {($freq == 100) || ($freq == 99)}
+        }
+
         r get foo
         assert_equal [r get foo] {bar}
         r config set maxmemory-policy noeviction