test: Fix some insecure config file permissions

[siegfriedweber]

Description

Fix some insecure config file permissions in the opensearch-dashboards integration test.

This change fixes the following warnings:

File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/action_groups.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/allowlist.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/audit.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/config.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/internal_users.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/nodes_dn.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/roles.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/roles_mapping.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/..2025_11_27_10_33_49.419458873/tenants.yml has insecure file permissions (should be 0600)

It does not fix the following warnings:

Directory /stackable/opensearch/config/opensearch-security has insecure file permissions (should be 0700)
Directory /stackable/opensearch/config/opensearch-security/..2025_11_27_10_27_27.1104253726 has insecure file permissions (should be 0700)
File /stackable/opensearch/config/opensearch-security/..data has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/action_groups.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/allowlist.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/audit.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/config.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/internal_users.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/nodes_dn.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/roles.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/roles_mapping.yml has insecure file permissions (should be 0600)
File /stackable/opensearch/config/opensearch-security/tenants.yml has insecure file permissions (should be 0600)

The previous warnings could be fixed by using separate volume mounts with a subPath for each configuration file. However, this is too much work for this temporary solution. The security configuration will be integrated in #43 and then all warnings will disappear.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
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Author

• Integration tests passed (for non trivial changes)

Reviewer

• Code contains useful comments
• Code contains useful logging statements
• (Integration-)Test cases added
• Documentation added or updated. Follows the style guide.
• Changelog updated
• Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

• Feature Tracker has been updated
• Proper release label has been added
• Links to generated (nightly) docs added
• Release note snippet added
• Add type/deprecation label & add to the deprecation schedule
• Add type/experimental label & add to the experimental features tracker

[labrenbe]

lgtm