Follow up on the #6809 (Reserve memory for host) to add global settings for upper/lower limit

[soreana]

ISSUE TYPE

• Improvement Request

SUMMARY

In the #6809 PR, @wido suggested to add a new global settings to bound the value of host.reserved.mem.mb global setting. Due to the tight schedule, we planed to add these setting in a new PR with different milestone.

Suggested global settings are:

Name	Description	Default value
host.reserved.mem.mb.lower.bound	Sets a lower bound for reserved memory in megabytes. It is not possible to reserve less than this amount for any host.	0
host.reserved.mem.mb.upper.bound	Sets a upper bound for reserved memory in megabytes. It is not possible to reserve more than this amount for any host. The default value is 1 Tbytes	1048576