Sniper rifle training: Fix missing victory sound, also disable controls at the end String freeze notice: This commit will display a caption with the string "Victory!". It does NOT violate the string freeze, as this string is already present in stub.lua.

Lua scripts for engine testing. These scripts are the same as other Lua scripts
in Hedgewars, but you ought to call `EndLuaTest(TEST_SUCCESSFUL)` or
`EndLuaTest(TEST_FAILED)` when the test is completed.