INSTALL.md is incomplete and/or outdated

##### ISSUE TYPE

* Documentation Report

##### COMPONENT NAME

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Build instructions
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##### CLOUDSTACK VERSION

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4.16
~~~

##### CONFIGURATION

##### OS / ENVIRONMENT

CentOS 7

##### SUMMARY

I tried to follow the steps in INSTALL.md to build CloudStack on CentOS 7. The instructions aren't working. They seem to be missing some steps, and I wonder if some of the dependency version numbers are outdated (e.g. Maven 3.6.3).

##### STEPS TO REPRODUCE

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##### EXPECTED RESULTS

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##### ACTUAL RESULTS

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I had to add a MySQL repository before yum could install MySQL. I didn't know which version to use, so I picked 7.5 because it's used in the quick installation guide.

```
wget http://repo.mysql.com/mysql-community-release-el7-5.noarch.rpm
rpm -ivh mysql-community-release-el7-5.noarch.rpm
```

In the `Install tools and dependencies` section, I needed to add bzip2 and python3 to the yum command.

The Maven download URL doesn't work. You could change the domain name from www.us.apache.org to archive.apache.org. That would work, but you'd still get an old version. I found it was much easier to just use sdkman.io to install the latest version.

Those changes were enough for the build to succeed. But I couldn't create the DB schema. I'm wondering if that part of the process needs an older version of MySQL.
~~~