allocator: fix flake in TestWatchRemoteKVStore

The TestWatchRemoteKVStore test is currently affected by a potential
source of flakiness because it directly asserts that the cache is
synchronized after validating that it has been registered. However,
the two operations are performed independently, and the on-sync
callback handler is invoked after having released the lock, which
implies that it may not have been invoked at check time. Let's get
this fixed by wrapping the check with Eventually.

Signed-off-by: Marco Iorio <marco.iorio@isovalent.com>

Author: giorio94

pkg/allocator/allocator_test.go

@@ -584,8 +584,11 @@ func TestWatchRemoteKVStore(t *testing.T) {
 		return global.remoteCaches["remote"] == rc
 	}, 1*time.Second, 10*time.Millisecond)
 
-	require.True(t, rc.Synced(), "The cache should now be synchronized")
-	require.True(t, synced.Load(), "The on-sync callback should have been executed")
+	require.EventuallyWithT(t, func(c *assert.CollectT) {
+		assert.True(c, rc.Synced(), "The cache should now be synchronized")
+		assert.True(c, synced.Load(), "The on-sync callback should have been executed")
+	}, 1*time.Second, 10*time.Millisecond)
+
 	stop(cancel)
 	require.False(t, rc.Synced(), "The cache should no longer be synchronized when stopped")