SUBMARINE-222. Use virtual Python env in CICD image

[tangzhankun]

What is this PR for?

When using the current CICD image, there is a possibility that the merge PR script will fail due to Python environment issue. I propose to use python virtual env to solve this.

What type of PR is it?

Improvement

What is the Jira issue?

https://issues.apache.org/jira/browse/SUBMARINE-222

How should this be tested?

re-build the cicd image and use it to merge PR

Questions:

• Does the licenses files need update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? No

[jojochuang]

Looks good.
Instead of downloading virtualenv source code & compile it, you should be able to just install it: as an example: https://gist.github.com/frfahim/73c0fad6350332cef7a653bcd762f08d

[xunliu]

I think it would be even better to add environment variables to the container's startup parameters.
Can you update the documentation(https://github.com/apache/hadoop-submarine/tree/master/dev-support/cicd#docker-mode), increase the startup parameters?

[yuanzac]

LGTM.
I've tested it. it works.
Thanks @tangzhankun @jojochuang @liuxunorg