tests: Document and rename fixture {adb => real_adb_device}
tests: Document and rename fixture {adb => real_adb_device}

LewisHaley/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,LewisHaley/stb-tester,stb-tester/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester,stb-tester/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester,LewisHaley/stb-tester