Improve test_cluster_drs.py for VMware

[shwstppr]

ISSUE TYPE

• Bug Report
• Improvement Request

COMPONENT NAME

Test

CLOUDSTACK VERSION

main/4.19

CONFIGURATION

NA

OS / ENVIRONMENT

NA

SUMMARY

Improve test_cluster_drs.py for VMware
test_02_balanced_drs_algorithm intermittently fails for VMware due to higher memory usage for system VMs as highlighted in #7344 (comment)

[shwstppr]

@vishesh92 do we need any work on this? I'm not seeing failures recently

[sureshanaparti]

Fixed in #8508