Describe the requested improvement

An instructor makes a gradeable chosing the submit by version control option:

If the server is configured to work with GIT access tokens (instead of vcs through scp using passwords) then the student sees this message:

(url, course, & username redacted)

Requested changes:

1. Let's add a couple sentences after the git clone line:

git clone https://submitty.REDACTEDURL.edu/git/s26/REDACTEDCOURSE/homework1/REDACTEDUSERNAME SPECIFY_TARGET_DIRECTORY

You will log in using `REDACTEDUSERNAME` as your username and VCS / GIT Authentication Token as the password.  Click the button below to generate a VCS / GIT Authentication Token for Submitty if this is your first time using GIT with Submitty.

(pasting in the user's submitty username into that sentence.)

2. The note:
   "Note: There may be a delay before your repository is prepared, please refer to assignment instructions."
   These instructions are stale and mostly unnecessary.

   It is from an earlier time when git repositories had to be created by the instructor. Here are those older instructions:

   https://submitty.org/instructor/assignment_preparation/managing_git#generating-submitty-server-version-control-repositories

   This is mostly unnecessary, but there is a situation where the instructor (or sysadmin) may need to manually call the script to make missing repositories. See also Create repository for new student and existing vcs gradeable #4931.

   We do not need to display this sentence if the student has a repository. Specifically, let's check for the existance of this directory:

   /var/local/submitty/vcs/git/s26/REDACTEDCOURSE/homework1/REDACTEDUSERNAME/

   If it exists, do not display that message. If it does not exist, do display the message. Actually we can strengthen the message to say "Contact your instructor or sysadmin for assistance in creating your repository for this assignment." or similar.

NOTE: Make sure this all does something reasonable to team repositories as well...