imagePullCredentialsType   
  The type of credentials CodeBuild uses to pull images in your build.
Valid values:
- CODEBUILDspecifies that CodeBuild uses its own credentials. This requires that you modify your ECR repository policy to trust the CodeBuild service principal.
- SERVICE_ROLEspecifies that CodeBuild uses your build project's service role.
When you use a cross-account or private registry image, you must use SERVICE_ROLE credentials. When you use an CodeBuild curated image, you must use CODEBUILD credentials.