Bug 1720403 - reenable what's new page on release for 90+. r=releng-r…

…eviewers,mtabara DONTBUILD

Turns out we only wanted to turn off the WNP on 89, not 89+.
Backs out 5efdc103f8dd

Differential Revision: https://phabricator.services.mozilla.com/D119831

browser/config/whats_new_page.yml

@@ -6,6 +6,17 @@
 - type: product-details
   # %LOCALE% is automatically replaced by Balrog.
   url: "https://www.mozilla.org/%LOCALE%/{product}/{version}/releasenotes/"
+- type: show-url
+  # yamllint disable-line rule:line-length
+  url: "https://www.mozilla.org/{product}/{version}/whatsnew/all/?oldversion=%OLD_VERSION%"
+  conditions:
+      blob-types: [wnp]
+      release-types: [release, release-rc]
+      products: [firefox]
+      update-channel: release
+      # e.g.: ["<61.0"]. {version.major_number} reflects the current version.
+      # This is done by taskgraph.
+      versions: ["<{version.major_number}.0"]
 - type: show-url
   # yamllint disable-line rule:line-length
   url: "https://www.mozilla.org/%LOCALE%/{product}/{version.major_number}.0beta/whatsnew/?oldversion=%OLD_VERSION%"