Make sure /home/venv is writeable by model-server user in dev docker image

[mreso]

Description

This PR moves the creation of the virtualenv to a place where we can change the owner to model-server without creating another layer. This ensures that users of the docker image can install packages without changing to root user.

Fixes #(issue)
#1499

Type of change

Please delete options that are not relevant.

• 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

Feature/Issue validation/testing

Please describe the tests [UT/IT] that you ran to verify your changes and relevant result summary. Provide instructions so it can be reproduced.
Please also list any relevant details for your test configuration.

• Test A
  Build docker with:
  ./build_image.sh -bt dev
  Start docker:
  docker run -ti --rm docker.io/pytorch/torchserve:dev-cpu bash
  model-server@90d7c57df607:~$ ls -la /home/
  total 16
  drwxr-xr-x 1 root root 4096 Mar 16 01:09 .
  drwxr-xr-x 1 root root 4096 Mar 16 02:21 ..
  drwxr-xr-x 4 model-server model-server 4096 Mar 16 01:09 model-server
  drwxr-xr-x 6 model-server root 4096 Mar 16 01:07 venv
  Run pip install [any package] to test if installing packages works

• Test B

• Logs

Checklist:

• Have you added tests that prove your fix is effective or that this feature works?
• Has code been commented, particularly in hard-to-understand areas?
• Have you made corresponding changes to the documentation?

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AWS CodeBuild CI Report

• CodeBuild project: torch-serve-build-cpu
• Commit ID: dceac4e
• Result: SUCCEEDED
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[sagemaker-neo-ci-bot]

AWS CodeBuild CI Report

• CodeBuild project: torch-serve-build-win
• Commit ID: dceac4e
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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[sagemaker-neo-ci-bot]

AWS CodeBuild CI Report

• CodeBuild project: torch-serve-build-gpu
• Commit ID: dceac4e
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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[sagemaker-neo-ci-bot]

AWS CodeBuild CI Report

• CodeBuild project: torch-serve-build-win
• Commit ID: dceac4e
• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository

[sagemaker-neo-ci-bot]

AWS CodeBuild CI Report

• CodeBuild project: torch-serve-build-gpu
• Commit ID: dceac4e
• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository