Improve docker image for RBE and re-enable RBE on main

[bclark8923]

Description

Please include a summary of the changes and the related issue. Please also
include relevant motivation and context.

Fixes #1297

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please also list any relevant details for your test configuration

Checklist

• Updated documentation if needed
• Tests added/amended
• bazel test //... passes locally
• PR is contained in a single commit, using git amend see some docs

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This change is 

[allada]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: 0 of 1 LGTMs obtained, and all files reviewed, and pending CI: Docs Deployment / macos-14

[allada]

Reviewable status: 1 of 1 LGTMs obtained, and all files reviewed, and pending CI: Docs Deployment / macos-14