Remove unneeded .txt dumps in codegen box tests

These are only used in diagnostic tests, and for codegen tests they are
basically useless.

compiler/testData/codegen/box/diagnostics/functions/inference/kt6176.txt

@@ -1,6 +0,0 @@
-package
-
-public fun box(): kotlin.String
-public fun </*0*/ R> foo(/*0*/ f: () -> R): R
-public fun </*0*/ T : kotlin.Any> some(/*0*/ v: T?, /*1*/ b: T): T
-public fun </*0*/ T : kotlin.Any> some1(/*0*/ v: T?, /*1*/ b: T): T