[FEATURE REQUEST] Ability to control if lvm grains are collected

[agraul]

Is your feature request related to a problem? Please describe.
LVM grains can take a long time when the system has a lot of volumes and volume groups.

Describe the solution you'd like
A configuration option for the minion.conf that controls if lvm grains are collected. It's default is True, i.e. the change is not changing the behavior for existing users.

Setting enable_lvm_grains: False stops the grains/lvm.py from being loaded by the Salt loader.

Describe alternatives you've considered
Improve the collection time, the problem is that it's hard to ensure that the information is returned within one second or less.

Additional context
On one particular system, the lvm.lvm grain function takes ~3 minutes.

Please Note
If this feature request would be considered a substantial change or addition, this should go through a SEP process here https://github.com/saltstack/salt-enhancement-proposals, instead of a feature request.