1757 combine lint os and possibly trufflehog jobs

Description

https://repo1.dso.mil/platform-one/private/big-bang/ironbank/ironbank-bootstrap/-/issues/1757

• In the parent pipeline, replaces the lint, secret-scan, and os-type stages into one stage called validate-container-metadata
• Combined the lint and os-type jobs into a job called lint-and-image-inspect in the validate-container-metadata stage
• Moved the trufflehog job into this stage
• Removed code from trigger.yaml that was not needed anymore
• Removed /stages/lint/validate-hardening-manifest.yaml since it is not being used anywhere
• Updated documentation to reflect these changes

Risk

Rollback Plan

Testing

• Tested in Mario with https://code-ib-mario.staging.dso.mil/dsop/rflynn/ubi8/-/pipelines/22000 and most recently with https://code-ib-mario.staging.dso.mil/dsop/rflynn/ubi8/-/pipelines/24481