udev: move the rules on systemd-enabled platforms to /usr/lib/udev

[lkundrak]

Description

The /etc directory contains user configuration, potentially overriding
the vendor-supplied rules that go to /usr/lib.

Let's prefer that directory on platforms that use systemd; we can be sure
that those platforms support rules in /usr/lib.

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This change is 

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@@            Coverage Diff             @@
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  Files              ?       78           
  Lines              ?    11175           
  Branches           ?     1578           
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  Hits               ?     7395           
  Misses             ?     3445           
  Partials           ?      335

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[lkundrak]

Hello?
Is there anybody out there?

[lkundrak]

Just nod if you can hear me

[lkundrak]

Is there anyone home?

[narrieta]

@trstringer could you take a look? thanks!

[lkundrak]

hello hello hello hello

[lkundrak]

ping ping

[lkundrak]

hi