Detect maven/gradle wrapper in sub directory

What does this MR do?

This change fixes a defect that occurs when a maven wrapper is present in a project that is located in a sub-directory from the root project. This occurs because the mvnw detection assumes that the mvnw is located in the root of the project rather than in a sub-directory. source

It also detects the gradlew from a sub-directory path. source

What are the relevant issue numbers?

gitlab-org/gitlab#273155 (closed)

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