e2e/compact: Revert change to downsample count assertion

Combined with the previous commit this effectively reverts
all of 2ed48f7, in which two assertions were changed to
(unknowingly) account for a bug which had just been
introduced in the downsampling code, causing duplicate blocks.

This assertion change I am less sure on the reasoning for,
but after running through the e2e tests several times locally,
it is consistent that the only downsampling happens in the
"compact-working" step, and so all other steps would report 0
for their total downsamples metric.

Signed-off-by: Thomas Hartland <[email protected]>

test/e2e/compact_test.go

@@ -775,7 +775,7 @@ func testCompactWithStoreGateway(t *testing.T, penaltyDedup bool) {
 		testutil.Ok(t, c.WaitSumMetricsWithOptions(e2emon.Equals(7), []string{"thanos_compact_group_compaction_runs_started_total"}, e2emon.WaitMissingMetrics()))
 		testutil.Ok(t, c.WaitSumMetricsWithOptions(e2emon.Equals(7), []string{"thanos_compact_group_compaction_runs_completed_total"}, e2emon.WaitMissingMetrics()))
 
-		testutil.Ok(t, c.WaitSumMetricsWithOptions(e2emon.Equals(2), []string{"thanos_compact_downsample_total"}, e2emon.WaitMissingMetrics()))
+		testutil.Ok(t, c.WaitSumMetricsWithOptions(e2emon.Equals(0), []string{"thanos_compact_downsample_total"}, e2emon.WaitMissingMetrics()))
 		testutil.Ok(t, c.WaitSumMetricsWithOptions(e2emon.Equals(0), []string{"thanos_compact_downsample_failures_total"}, e2emon.WaitMissingMetrics()))
 
 		testutil.Ok(t, str.WaitSumMetricsWithOptions(