tests: avoid compat code in --no-compat mode (#347)

Simply drop because the `require`s are not actually used by the tests
and no file from `compat/` should be loaded unconditionally. (This can
otherwise lead to incorrect results for `brew tests --no-compat`.)

Library/Homebrew/test/test_formula_installer.rb

@@ -1,6 +1,5 @@
 require "testing_env"
 require "formula"
-require "compat/formula_specialties"
 require "formula_installer"
 require "keg"
 require "tab"

Library/Homebrew/test/test_formula_installer_bottle.rb

@@ -1,6 +1,5 @@
 require "testing_env"
 require "formula"
-require "compat/formula_specialties"
 require "formula_installer"
 require "keg"
 require "tab"