Before this commit source had been compiling with inconsistent
`erl_opts` under test profile with `PROFILE` env set to `emqx`.
```
{compile_info,[{emqx_vsn,"5.0.0-beta.5-g948d4170"}]},
{d,'EMQX_RELEASE_EDITION',ce},
```
Instead stop passing `emqx_vsn` through compile options as is
expected by `emqx_release:version/0`.
Testcase `t_log_file` was flapping when run happened to pass through
boundary of a second. Archive files' `ctime`s could differ between
consecutive archive downloads.
Even though relx 4.7.0 seems to support passing overlay vars through
`overlay_vars` option, it was designed to hold list of filenames where
vars are defined and works unreliable if used as a proplist.
reason: 'ce' (Community Edition) is only for internal use,
when it comes to user/customer facing descriptions,
we should use Opensource edition and Enterprise edition.
Similary, for user/customer facing shell prompt,
use `v` for Opensource edition and `e` for Enterprise