Update minitest plugin for junit-XML generation
ci_reporter_minitest is old and seems unmaintained. With minitest 5.11 the generated XML doesn't contain the test class names.
Fixes #26968 - Switch to minitest-reporters
ci_reporter_minitest is unmaintained and since minitest 5.1 it no longer
shows the class names. minitest-reporters does.
#3 Updated by Ewoud Kohl van Wijngaarden about 2 years ago
In kafo we changed to minitest-reporters. See https://github.com/theforeman/kafo/commit/25733d0f65458956a87f09e8646cd4b153c6c0b1 for reference.