Remove unused checkout.sh script and set runner explicitly (#217)

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# PR Details
## Description
Remove unused checkout script and explicitly define runner
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## Related GitHub Issue

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## Related Jira Key

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## Motivation and Context
Remove unused scripts
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## How Has This Been Tested?
CI
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## Types of changes

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- [ ] Defect fix (non-breaking change that fixes an issue)
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- [ ] Breaking change (fix or feature that cause existing functionality
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## Checklist:

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- [ ] I have added any new packages to the sonar-scanner.properties file
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.
- [ ] I have read the
[**CONTRIBUTING**](https://github.com/usdot-fhwa-stol/carma-platform/blob/develop/Contributing.md)
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- [ ] I have added tests to cover my changes.
- [ ] All new and existing tests passed.

.github/workflows/docker.yml

@@ -2,7 +2,8 @@ name: Docker build
 on:
   pull_request:
     types: [opened, synchronize, reopened]
-
 jobs:
   docker:
     uses: usdot-fhwa-stol/actions/.github/workflows/docker.yml@main
+    with:
+      runner: ubuntu-latest-16-cores

.github/workflows/dockerhub.yml

@@ -2,8 +2,8 @@ name: Docker Hub build
 on:
   push:
     branches:
-      - "develop"
-      - "master"
+      - develop
+      - master
       - "release/*"
     tags:
       - "carma-system-*"
@@ -14,3 +14,5 @@ jobs:
     secrets:
       DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
       DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
+    with:
+      runner: ubuntu-latest-16-cores