Always align scrapes even if tolerance is bigger than 1% of scrape interval

When the scrape tolerance is bigger than 1% of the scrape interval, take
1% of the scrape interval as the tolerance instead of not aligning the
scrape at all.

Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu>

scrape/scrape.go

@@ -1192,14 +1192,18 @@ mainLoop:
 		// Calling Round ensures the time used is the wall clock, as otherwise .Sub
 		// and .Add on time.Time behave differently (see time package docs).
 		scrapeTime := time.Now().Round(0)
-		if AlignScrapeTimestamps && sl.interval > 100*ScrapeTimestampTolerance {
+		if AlignScrapeTimestamps {
+			tolerance := ScrapeTimestampTolerance
+			if maxTolerance := sl.interval / 100; tolerance < maxTolerance {
+				tolerance = maxTolerance
+			}
 			// For some reason, a tick might have been skipped, in which case we
 			// would call alignedScrapeTime.Add(interval) multiple times.
 			for scrapeTime.Sub(alignedScrapeTime) >= sl.interval {
 				alignedScrapeTime = alignedScrapeTime.Add(sl.interval)
 			}
 			// Align the scrape time if we are in the tolerance boundaries.
-			if scrapeTime.Sub(alignedScrapeTime) <= ScrapeTimestampTolerance {
+			if scrapeTime.Sub(alignedScrapeTime) <= tolerance {
 				scrapeTime = alignedScrapeTime
 			}
 		}