[Directories] Set /etc permissions to 0755.

[gmarciani]

Description of changes

Set /etc permissions to 0755.
This is the default permission in Linux, but it was unintentionally changed in Rocky9.4 (https://forums.rockylinux.org/t/changed-permissions-on-etc-in-rl9-4-genericcloud-image/14449) breaking Munge, which requires the folder to be 0755.

Tests

• Spec test cookbooks/aws-parallelcluster-platform/spec/unit/recipes/directories_spec.rb
• [ONGOING] Build image in Rocky9.4
• [PENDING] integ test createami.test_createami.test_build_image

References

• Link to impacted open issues.
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