perf: report more of the higher range in perfrevlogwrite

Since the delta chain length is limited to 1000 revisions, we get a new
snapshot about every 1000 revisions. If we assume that the snapshot will be
most of the slowest revision, the current display (99% and max) are not very
precise in their area. We now include more information about this space in the
default report.

contrib/perf.py

@@ -1797,6 +1797,9 b' def perfrevlogwrite(ui, repo, file_=None'
         ("90%", resultcount * 90 // 100),
         ("95%", resultcount * 95 // 100),
         ("99%", resultcount * 99 // 100),
+        ("99.9%", resultcount * 999 // 1000),
+        ("99.99%", resultcount * 9999 // 10000),
+        ("99.999%", resultcount * 99999 // 100000),
         ("max", -1),
     ]
     if not ui.quiet: