Update apache_max_clients default
Update apache_max_clients default

`apache_max_clients` config is used for the `MaxRequestWorkers` setting. With a value of `128`, Apache will show a Warning:
`WARNING: MaxRequestWorkers of 128 is not an integer multiple of ThreadsPerChild of 25, decreasing to nearest multiple 125, for a maximum of 5 servers.`

Setting this config to 125 in the boxfile.yml removes the warning. Having 125 as the default value should remove the warning without additional effort from the user.
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