Remove verbose flag in pip command

What does this MR do?

This change removes the verbose (-v) flag from the pip command invoked to install detected packages in a virtualenv

The presence of verbose flag causes a lot of logs to be produced which ends up running over GitLab.com (SaaS) log limits and makes it difficult to troubleshoot failures

The verbose flag was added during gitlab-org/security-products/license-management!133 possibly for just debug reasons during its development

What are the relevant issue numbers?

Related to gitlab-org/security-products/license-management!133

Related to customer support ticket https://gitlab.zendesk.com/agent/tickets/276040

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Job definition example
  • CI Templates (to be removed)
  • Vendored CI Templates (also in CE)
  • Ensure that all of the ENV vars supported are propagated to Docker containers upon docker run in job definitions
• Conforms to the code review guidelines
• Security reports checked/validated by reviewer