Revert "Use pylint 2.7 for depot_tools"

This reverts commit 22bf605bb63f8ff01aa7c1a2841718e3489b43d6.

Reason for revert: breaks gclient sync

Original change's description:
> Use pylint 2.7 for depot_tools
>
> This includes a few fixes for specific errors, and disables several new
> warnings introduced in this version, in order to allow for an incremental migration.
>
> Bug:1262286
> Change-Id: Ie97d686748c9c952e87718a65f401c5f6f80a5c9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3400616
> Reviewed-by: Gavin Mak <gavinmak@google.com>
> Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>

Bug: 1262286
Change-Id: Ieb946073c7886c7bf056ce843a5a48e82becf7a5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3413672
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
diff --git a/metrics_utils.py b/metrics_utils.py
index 96982a9..7097857 100644
--- a/metrics_utils.py
+++ b/metrics_utils.py
@@ -54,8 +54,7 @@
 def get_change_notice(version):
   if version == 0:
     return [] # No changes for version 0
-
-  if version == 1:
+  elif version == 1:
     return [
       'We want to collect the Git version.',
       'We want to collect information about the HTTP',
@@ -65,8 +64,7 @@
       'We only collect known strings to make sure we',
       'don\'t record PII.',
     ]
-
-  if version == 2:
+  elif version == 2:
     return [
       'We will start collecting metrics from bots.',
       'There are no changes for developers.',