This attempts to unify SELinux handling in the tests. It moves the
package installation to the acceptance spec helper to reduce
duplication. It then makes the set_apache_defaults line idempotent and
restorecon_apache correctly chained. This works around [PUP-10548] which
is that Puppet doesn't reload file contexts within a run. That means it
must first create the file(s) and then run restorecon to get correct
contexts.

[PUP-10548]: https://tickets.puppetlabs.com/browse/PUP-10548

Clean up SELinux handling in acceptance testing.

add LimitRequestLine parameter

…que_id-naming

remove _module from apache::mod::unique_id name.

there were a few things broken:
* a2dismod was called with the wrong module name. at least on apache
  2.4.54 on Debian 11 it is named mpm_event, not event
* the paths to the files were wrong
* a2dismod already purges the .load and .conf file, the exec resources
  are not required (even then a file resource would probably be cleaner
  to purge them)
* Apache needs to be reloaded, so just running this priot to
  apache2::service isn't enough, it needs to be a notify

This initially worked but was changed from mpm_event to event in
#1961. Then it was
fixed in #2034 by
adding the exec resources, but the actual a2dismod was still broken.

disable::mpm_event: Fix module deactivation