BCDA-7991: Address sonarqube security issues

[alex-dzeda]

🎫 Ticket

https://jira.cms.gov/browse/BCDA-7991

🛠 Changes

Updated Dockerfile + problematic html file.

ℹ️ Context for reviewers

SonarQube had 8 "findings" related to the static site application: 2 related to the Dockerfile in the project, and 6 related to external link outs. 7 of those findings will be resolved with this PR, and one can remain ignored (the copying all files in a directory in the Dockerfile) as it's mitigated by addressing the second Dockerfile finding (ensuring that the docker container runs in user mode)

✅ Acceptance Validation

Addressed/mitigated each security issue by ensuring the Dockerfile specifies the use of a non-root user and adding rel="noopener" tags.

🔒 Security Implications

• This PR adds a new software dependency or dependencies.
• This PR modifies or invalidates one or more of our security controls.
• This PR stores or transmits data that was not stored or transmitted before.
• This PR requires additional review of its security implications for other reasons.

If any security implications apply, add Jason Ashbaugh (GitHub username: StewGoin) as a reviewer and do not merge this PR without his approval.

[laurenkrugen-navapbc]

LGTM! Thanks for addressing these.