DAOS-16713 vos: initialize checkpoint stats

[NiuYawei]

Initialize checkpoint stats to zero.

Skip-func-hw-test-medium-md-on-ssd: false
Skip-func-hw-test-large-md-on-ssd: false

Required-githooks: true

Before requesting gatekeeper:

• Two review approvals and any prior change requests have been resolved.
• Testing is complete and all tests passed or there is a reason documented in the PR why it should be force landed and forced-landing tag is set.
• Features: (or Test-tag*) commit pragma was used or there is a reason documented that there are no appropriate tags for this PR.
• Commit messages follows the guidelines outlined here.
• Any tests skipped by the ticket being addressed have been run and passed in the PR.

Gatekeeper:

• You are the appropriate gatekeeper to be landing the patch.
• The PR has 2 reviews by people familiar with the code, including appropriate owners.
• Githooks were used. If not, request that user install them and check copyright dates.
• Checkpatch issues are resolved. Pay particular attention to ones that will show up on future PRs.
• All builds have passed. Check non-required builds for any new compiler warnings.
• Sufficient testing is done. Check feature pragmas and test tags and that tests skipped for the ticket are run and now pass with the changes.
• If applicable, the PR has addressed any potential version compatibility issues.
• Check the target branch. If it is master branch, should the PR go to a feature branch? If it is a release branch, does it have merge approval in the JIRA ticket.
• Extra checks if forced landing is requested
  • Review comments are sufficiently resolved, particularly by prior reviewers that requested changes.
  • No new NLT or valgrind warnings. Check the classic view.
  • Quick-build or Quick-functional is not used.
• Fix the commit message upon landing. Check the standard here. Edit it to create a single commit. If necessary, ask submitter for a new summary.

[github-actions]

Ticket title is 'telemetry/wal_metrics.py:WalMetrics.test_wal_checkpoint_metrics- json: unsupported value: NaN'
Status is 'In Review'
Labels: 'daily_test,md_on_ssd2,ci_master_daily'
https://daosio.atlassian.net/browse/DAOS-16713

[tanabarr]

does this need to run with Features: telemetry ?

[daosbuild1]

Test stage Functional Hardware Medium completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15454/1/execution/node/1641/log

[daosbuild1]

Test stage Functional Hardware Large completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15454/2/execution/node/1466/log

[daosbuild1]

Test stage Functional Hardware Large MD on SSD completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15454/2/execution/node/1450/log

[daosbuild1]

Test stage Functional Hardware Medium Verbs Provider completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15454/2/execution/node/1703/log

[daosbuild1]

Test stage Functional Hardware Medium completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15454/2/execution/node/1657/log

[daosbuild1]

Test stage Functional Hardware Medium MD on SSD completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-15454/2/execution/node/1641/log

[NiuYawei]

@daos-stack/daos-gatekeeper , the test showed that the issue is fixed by the patch. These CI failures are from daily tests (The issue was on md-on-ssd daily, so I enabled daily test for this PR), let's force land it.