Introducing size 1x.extra-small as production support for LokiStack in OpenShift 4

Issue

• Introducing size between 1x.extra-small and 1x.small for LokiStack because as per sizing guide for LokiStack, size 1x.extra-small is for Demo use only and 1x.small is too large for users with smaller clusters or clusters with little load.
• Define resource requirements for 1x.extra-small production support.