Update experiment status chip text and color

[zackcl]

Make the following changes to the status chip text in the UI only:

• Enrolling -> Running
• Enrollment Complete -> Paused
• Cancelled -> Completed

Also, these colors should be applied to each status:

  --status-running: #3366ff;
  --status-paused: #6478c8;
  --status-completed: #33cc66;

We will leave the status enums (EXPERIMENT_STATE, STATUS_INDICATOR_CHIP_TYPE) unchanged for now. But we should add comments and remove unused statuses (e.g., Draft).