Add option to specify clone path

What does this MR do?

Replaces !876 (closed).

It adds support for specifying GIT_CLONE_PATH, enabled by default for docker/kubernetes executor.

Please read: !876 (closed)

Why was this MR needed?

Closes #2211 (closed)

Are there points in the code the reviewer needs to double check?

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Added tests for this feature/bug
• In case of conflicts with master - branch was rebased

What are the relevant issue numbers?

• blocked by !1282 (merged)