Make it use the mirror by default, and add necessary headers

[dan-hipschman]

Context

This branch has image tag mirror-1.

See this slack thread for why the headers are needed: https://opendoor.slack.com/archives/C066PGLK77B/p1714072860609209

This also makes the mirror the default, since we plan to use it everywhere, it'll save typing in the pipelines.

Test Plan

Tested this out on one of our pipelines and it works.

Mitigation

Checklist

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to external documentation if necessary (READMEs, Confluence, etc.)
• I have checked that other PRs this PR depends on have already been deployed.
• I can confirm that if this PR introduces a DB schema change, I have read and followed all the steps outlined in the Data Contract.