buildserver: remove special sshd setup for Ubuntu 14.04

Now that fdroidserver requires Python 3, there's no need to tune sshd for
an old version of Paramiko because Ubuntu 14.04 does not have
python3-paramiko package in its repositories:

    https://packages.ubuntu.com/search?keywords=python3-paramiko

We can safely assume that Ubuntu 14.04 users have installed a more recent
version of Paramiko from PIP.

MANIFEST.in

@@ -7,7 +7,6 @@ include buildserver/provision-apt-proxy
 include buildserver/provision-gradle
 include buildserver/provision-pip
 include buildserver/provision-qt-sdk
-include buildserver/provision-ubuntu-trusty-paramiko
 include buildserver/setup-env-vars
 include buildserver/Vagrantfile
 include completion/bash-completion

buildserver/Vagrantfile

@@ -80,9 +80,4 @@ Vagrant.configure("2") do |config|
   config.vm.provision "file", source: "gradle",
     destination: "/opt/gradle/bin/gradle"
 
-  # let Ubuntu/trusty's paramiko work with the VM instance
-  if `uname -v`.include? "14.04"
-    config.vm.provision "shell", path: "provision-ubuntu-trusty-paramiko"
-  end
-
 end

buildserver/provision-ubuntu-trusty-paramiko

@@ -1,19 +0,0 @@
-#!/bin/bash
-
-echo $0
-set -e
-
-# Ubuntu trusty 14.04's paramiko does not work with jessie's openssh's default settings
-# https://stackoverflow.com/questions/7286929/paramiko-incompatible-ssh-peer-no-acceptable-kex-algorithm/32691055#32691055
-
-if ! grep --quiet ^Ciphers /etc/ssh/sshd_config; then
-    echo Ciphers aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes128-ctr >> /etc/ssh/sshd_config
-fi
-
-if ! grep --quiet ^MACs /etc/ssh/sshd_config; then
-    echo MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,hmac-ripemd160,hmac-sha1 >> /etc/ssh/sshd_config
-fi
-
-if ! grep --quiet ^KexAlgorithms /etc/ssh/sshd_config; then
-    echo KexAlgorithms diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1 >> /etc/ssh/sshd_config
-fi