fix bug in pct calculation in memory usage alert

[Sohamdg081992]

PR Description

fix bug in pct calculation in memory usage alert.

I have deployed this fix for near ring clusters wcus and euseuap.

New Feature Checklist

• [ ] List telemetry added about the feature.
• [ ] Link to the one-pager about the feature.
• [ ] List any tasks necessary for release (3P docs, AKS RP chart changes, etc.) after merging the PR.
• [ ] Attach results of scale and perf testing.

Tests Checklist

• [ ] Have end-to-end Ginkgo tests been run on your cluster and passed? To bootstrap your cluster to run the tests, follow these instructions.
  • Labels used when running the tests on your cluster:
  • [ ] operator
  • [ ] windows
  • [ ] arm64
  • [ ] arc-extension
  • [ ] fips
• [ ] Have new tests been added? For features, have tests been added for this feature? For fixes, is there a test that could have caught this issue and could validate that the fix works?
  • [ ] Is a new scrape job needed?
  • [ ] The scrape job was added to the folder test-cluster-yamls in the correct configmap or as a CR.
  • [ ] Was a new test label added?
  • [ ] A string constant for the label was added to constants.go.
  • [ ] The label and description was added to the test README.
  • [ ] The label was added to this PR checklist.
  • [ ] The label was added as needed to testkube-test-crs.yaml.
  • [ ] Are additional API server permissions needed for the new tests?
  • [ ] These permissions have been added to api-server-permissions.yaml.
  • [ ] Was a new test suite (a new folder under /tests) added?
  • [ ] The new test suite is included in testkube-test-crs.yaml.