"exit $?" raises TypeError on Ruby 2.0
runit: rcmds is newline-delimited

Fixes #30032
Remove default values from formula constructor parameters

Closes #30017.
aplus: disable X
Stop caching Superenv.bin

It is not a hotspot and causes an ordering dependency in the tests.
Remove ruby-prof rake task

The areas that we are interested in optimizing for performance are
things that are invoked repeatedly, and are not evident in the test
suite.
Remove rcov rake task

rcov is not compatible with Ruby 2.0.
aplus: --without-x doesn't work
Simplify test setup
Use external interface in tests
Move updater mock into test class namespace
Pull mock initialization code into initialize
Extract constant strings
Pull common code into setup method
Trust the fixtures and stop asserting on file(1) output
Add methods for building test file paths
Scope setup to the tests that need it
Remove ABS__FILE constant from test environment
Rename TEST_FOLDER to TEST_DIRECTORY
Remove unnecessary code