release.sh: sunset release announcement email

I'm not sure if our peer projects do this or if it's useful to have
on top of github releases (especially as most releases are patch
releases mainly).

We could certainly use "sphinx-build -b text" in
build_tools/release-notes.sh to extract a nice plaintext changelog
and send that, but that doesn't support links.  Not sure about HTML
email either.

build_tools/release.sh

@@ -201,7 +201,7 @@ done
     git push git@github.com:$repository_owner/fish-site HEAD:master
 )
 
-if [ -n "$integration_branch" ]; then
+if [ -n "$integration_branch" ]; then {
     git push $remote "$version^{commit}":refs/heads/$integration_branch
 else
     changelog=$(cat - CHANGELOG.rst <<EOF
@@ -213,21 +213,6 @@ EOF
     printf %s\\n "$changelog" >CHANGELOG.rst
     CommitVersion ${version}-snapshot "start new cycle"
     git push $remote HEAD:master
-fi
-
-# TODO This can currently require a TTY for editing and password
-# prompts.
-if [ "$repository_owner" = fish-shell ]; then {
-    mail=$(mktemp)
-    cat >$mail <<EOF
-From: $(git var GIT_AUTHOR_IDENT | sed 's/ [0-9]* +[0-9]*$//')
-Subject: fish $version released
-
-See https://github.com/fish-shell/fish-shell/releases/tag/$version
-EOF
-    git send-email --suppress-cc=all --confirm=always $mail \
-        --to="fish-users Mailing List <fish-users@lists.sourceforge.net>"
-    rm $mail
 } fi
 
 exit