Remove stale announcement

This announcement was live when the v1.19 release branch was made,
but is no longer active.

(Since this release, we updated the mechanism for publishing
announcements, but have not backported those changes).

config.toml

@@ -156,7 +156,7 @@ github_repo = "https://github.com/kubernetes/website"
 
 # param for displaying an announcement block on every page.
 # See /i18n/en.toml for message text and title.
-announcement = true
+announcement = false
 announcement_bg = "#000000" #choose a dark color – text is white
 
 #Searching