operator: Fix custom CA for object-store in ruler component

[periklis]

What this PR does / why we need it:
Fix assigning custom CA bundle volume/volumeMount to ruler statefulset for object storage operations.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• CHANGELOG.md updated
  • If the change is worth mentioning in the release notes, add add-to-release-notes label
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[github-actions]

Trivy scan found the following vulnerabilities:

• HIGH openssl: Incorrect cipher key and IV length processing in libcrypto3 v3.1.2-r0. Fixed in v3.1.4-r0
• HIGH openssl: Incorrect cipher key and IV length processing in libssl3 v3.1.2-r0. Fixed in v3.1.4-r0

[xperimental]

Looks like it should fix the issue, though I did not get to testing this in a cluster yet. One small nitpick.