remove open() pythoneval test (python#8908)

python/typeshed#3371 causes this to produce a different error message. open()
with no arguments doesn't seem like an important use case, so testing for it
explicitly in pythoneval isn't all that useful.

test-data/unit/pythoneval.test

@@ -287,17 +287,14 @@ _program.py:3: note: Revealed type is 'typing.BinaryIO'
 _program.py:5: note: Revealed type is 'typing.IO[Any]'
 
 [case testOpenReturnTypeInferenceSpecialCases]
-reveal_type(open())
 reveal_type(open(mode='rb', file='x'))
 reveal_type(open(file='x', mode='rb'))
 mode = 'rb'
 reveal_type(open(mode=mode, file='r'))
 [out]
-_testOpenReturnTypeInferenceSpecialCases.py:1: error: Too few arguments for "open"
-_testOpenReturnTypeInferenceSpecialCases.py:1: note: Revealed type is 'typing.TextIO'
+_testOpenReturnTypeInferenceSpecialCases.py:1: note: Revealed type is 'typing.BinaryIO'
 _testOpenReturnTypeInferenceSpecialCases.py:2: note: Revealed type is 'typing.BinaryIO'
-_testOpenReturnTypeInferenceSpecialCases.py:3: note: Revealed type is 'typing.BinaryIO'
-_testOpenReturnTypeInferenceSpecialCases.py:5: note: Revealed type is 'typing.IO[Any]'
+_testOpenReturnTypeInferenceSpecialCases.py:4: note: Revealed type is 'typing.IO[Any]'
 
 [case testPathOpenReturnTypeInference]
 from pathlib import Path