Bug 1566393 - Set expires to "never" for inspector shadowdom scalars r=janerik

Depends on D38291

See input from Harald at https://bugzilla.mozilla.org/show_bug.cgi?id=1566383#c2
We would like to revive those scalars to help us monitor usage of inspector shadowdom features.

Differential Revision: https://phabricator.services.mozilla.com/D38308

--HG--
extra : moz-landing-system : lando

toolkit/components/telemetry/Scalars.yaml

@@ -1855,9 +1855,10 @@ devtools.shadowdom:
   shadow_root_displayed:
     bug_numbers:
       - 1470128
+      - 1566393
     description: >
       Whether the markup view displayed any #shadow-root element in the UI.
-    expires: "66"
+    expires: "never"
     kind: boolean
     notification_emails:
       - dev-developer-tools@lists.mozilla.org
@@ -1873,9 +1874,10 @@ devtools.shadowdom:
   shadow_root_expanded:
     bug_numbers:
       - 1470128
+      - 1566393
     description: >
       Whether the user expanded any #shadow-root element.
-    expires: "66"
+    expires: "never"
     kind: boolean
     notification_emails:
       - dev-developer-tools@lists.mozilla.org
@@ -1891,10 +1893,11 @@ devtools.shadowdom:
   reveal_link_clicked:
     bug_numbers:
       - 1470128
+      - 1566393
     description: >
       Whether the user clicked on any "reveal" link. "reveal" links are displayed in
       shadow dom trees in the markup view.
-    expires: "66"
+    expires: "never"
     kind: boolean
     notification_emails:
       - dev-developer-tools@lists.mozilla.org