Update blink_devtools to include blink tag

This allows OWNERS of blink_devtools to differentiate e-mails sent for
blink_devtools from the other devtools watchlist.

Also update the blink_devtools definition to not include
third_party/WebKit, as that folder has now been removed.

Change-Id: I97a9bcecac53d0439d95d1493cc95bb396642693
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1715067
Auto-Submit: Tim van der Lippe <tvanderlippe@google.com>
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680400}

WATCHLISTS

@@ -337,7 +337,7 @@
                   '|third_party/blink/renderer/core/frame/device_single_window_event_controller'
     },
     'blink_devtools': {
-      'filepath': 'third_party/(WebKit|blink)/.*(inspector|DevTools|dev_tools|devtools)',
+      'filepath': 'third_party/blink/.*(inspector|DevTools|dev_tools|devtools)',
     },
     'blink_dom': {
       'filepath': 'third_party/blink/renderer/core/dom/'
@@ -2041,7 +2041,7 @@
                                  'timvolodine@chromium.org'],
     'blink_devtools': ['apavlov+blink@chromium.org',
                        'caseq+blink@chromium.org',
-                       'devtools-reviews@chromium.org',
+                       'devtools-reviews+blink@chromium.org',
                        'lushnikov+blink@chromium.org',
                        'pfeldman+blink@chromium.org'],
     'blink_dom': ['blink-reviews-dom@chromium.org',