tests/functional2/lang: Drop trivial "parse-okay-1"

This really looks like one of the first tests ever written, it doesn't
seem to be actively testing anything interesting

Change-Id: I442840db932203c25da2d8400ada791f8aed04ce

tests/functional/lang/parse-okay-1.exp

@@ -1,19 +0,0 @@
-_type: ExprLambda
-body:
-  _type: ExprConcatStrings
-  es:
-    - _type: ExprConcatStrings
-      es:
-        - _type: ExprVar
-          value: x
-        - _type: ExprVar
-          value: y
-      isInterpolation: false
-    - _type: ExprVar
-      value: z
-  isInterpolation: false
-formals:
-  x: null
-  y: null
-  z: null
-formalsEllipsis: false

tests/functional/lang/parse-okay-1.nix

@@ -1 +0,0 @@
-{x, y, z}: x + y + z