Migrate to ubuntu-22 hub package for generating docs. Ubuntu-16 hub packages are removed in master/3.24.0

Ticket: none

Author: craigcomstock

generator/build/latest_nightly.sh

@@ -7,7 +7,7 @@ GREP_EXPR="${2:?undefined}" # usually jenkins-master-nightly-pipeline
 curl --silent "$BUILDCACHE_URL" | grep "$GREP_EXPR" | sed -r 's_.*<a href="([^"/]*)/">.*_\1_' | sort -rn | while read -r build; do
     # $build is something like jenkins-master-nightly-pipeline-962
     # verify that it has a deb file
-    url="$BUILDCACHE_URL/$build/PACKAGES_HUB_x86_64_linux_ubuntu_16/"
+    url="$BUILDCACHE_URL/$build/PACKAGES_HUB_x86_64_linux_ubuntu_22/"
     if curl --silent "$url" | grep -qF '.deb</a>'; then
         echo "$build"
         break