Get rid of the hard LVM dependency in elemental-toolkit

[davidcassany]

Is your feature request related to a problem? Please describe.
I am wondering if we could remove the LVM stack requirement from elemental.

We only need due to this code

elemental-toolkit/pkg/elemental/elemental.go

Lines 657 to 666 in 3ea9d75

	// DeactivateDevice deactivates unmounted the block devices present within the system.
	// Useful to deactivate LVM volumes, if any, related to the target device.
	func (e Elemental) DeactivateDevices() error {
	out, err := e.config.Runner.Run(
	"blkdeactivate", "--lvmoptions", "retry,wholevg",
	"--dmoptions", "force,retry", "--errors",
	)
	e.config.Logger.Debugf("blkdeactivate command output: %s", string(out))
	return err
	}

blkdeactivate is provided by the LVM package.

Describe the solution you'd like

I am wondering if shouldn't we just make a best effort call, if the command is not there only log it can't be executed but do nothing and do not return error. If it is there then normally execute it. We could even consider swallowing any error and just log it. If the target device is managed by lvm somehow it will also fail in later steps in any case.

With this change we could consider dropping lvm requirement from elemental package.