Fix: don't add cache size when write failed

[lee3164]

• Closes #### Required checklist
• Sample config files updated (both /etc folder and NewDemoConfig methods) (influxdb and plutonium)
• openapi swagger.yml updated (if modified API) - link openapi PR
• Signed CLA (if not already signed)

Description

fix a bug when write cache failed, cache size shouldn't increase.

Note for reviewers:

Check the semantic commit type:

• Feat: a feature with user-visible changes
• Fix: a bug fix that we might tell a user “upgrade to get this fix for your issue”
• Chore: version bumps, internal doc (e.g. README) changes, code comment updates, code formatting fixes… must not be user facing (except dependency version changes)
• Build: build script changes, CI config changes, build tool updates
• Refactor: non-user-visible refactoring
• Check the PR title: we should be able to put this as a one-liner in the release notes