lvm2 not starting lvm2-lvmetad on package install

[Impact]

 * On Xenial after installing lvm2, you must reboot before you are able to run vgcreate.
 * The package installer should be starting lvmetad.service.
 * $ sudo vgcreate localvg
  /run/lvm/lvmetad.socket: connect failed: No such file or directory
  WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
  Please enter a physical volume path.
  Run `vgcreate --help' for more information.

[Test Case]

 * Running the below commands result in the following error.

   $ sudo apt install lvm2
   $ sudo pvcreate /dev/sdb1
   $ sudo vgcreate localvg /dev/sdb1
  /run/lvm/lvmetad.socket: connect failed: No such file or directory
  WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
  Please enter a physical volume path.
  Run `vgcreate --help' for more information.

[Regression Potential]

 * Solution TBD, opening the bug so I don't forget this in the midst of a sprint.

 * discussion of how regressions are most likely to manifest as a result of this change.

 * It is assumed that any SRU candidate patch is well-tested before
   upload and has a low overall risk of regression, but it's important
   to make the effort to think about what ''could'' happen in the
   event of a regression.

 * This both shows the SRU team that the risks have been considered,
   and provides guidance to testers in regression-testing the SRU.

[Other Info]

 * Anything else you think is useful to include
 * Anticipate questions from users, SRU, +1 maintenance, security teams and the Technical Board
 * and address these questions in advance