https://emqx.atlassian.net/browse/EMQX-6978
[Related EIP](c4864eeccb/active/0022-forward-check-install-upgrade-script.md)
Currently, when performing a hot upgrade, the scripts that are run are
those from the currently installed EMQX version. It has a validation
that prevents upgrade between different minor versions. If we want to
allow an upgrade from, say, 5.0.x to 5.1.y, then the scripts in
already released packages will deny such operation. Also, if an
upgrade installation script contains a bug in the current, it will
never be able to execute properly without manual patching.
By attempting to execute the scripts from the target version, we may
add fixes and new validations to new EMQX versions and have them
executed by older versions.
for remsh prefixed nodes, ekka pick a random port to listen on
instead of following the conventional port mapping rule:
ekka listens on 4370 for emqx or emqx0 and 4371 for emqx1 and so on
OTP release handler only works with .tar.gz
as a result, we had to unpack .zip and re-pack .tar.gz
just to make OTP happy.
Now since we will be building .tar.gz packages
there is no need for this re-pack step anymore
The `install_upgrade.escript` depended on being able to retrieve the
`vm_args` argument from `init`, but that options has been removed
recently. Since this backup was unused, we also remove it here.
JimMoen