upgrade: remove redundant conditional

Since e1c62c35465eb6149688c745e4309438c08c410b, we exit early if the
outdated array is empty, so we no longer need to check this before
proceeding.
upgrade: move require out of method body
upgrade: make condition clearer
upgrade: don't rely on return value of 'onoe'
Percona Server 5.5.32-31.0

Closes #21243.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
percona-server: fix bin audit