Revert "add a lint to warn on implicit string concatenation (pantsbui…

…ld#7286)" (pantsbuild#7340)

This reverts commit 3a81e86.

### Problem

The use of the `asttokens` library, now within the pythonstyle checker pex, is causing a variant of pantsbuild#7158 when consumed outside of this repo. Additionally, some files fail to parse with:
```
    for tok in tokenize.generate_tokens(StringIO(str_node_text).readline):
  File "/opt/ee/python/2.7/lib/python2.7/tokenize.py", line 374, in generate_tokens
    ("<tokenize>", lnum, pos, line))
  File "<tokenize>", line 3
    "else echo 'no_op'; fi)"
```

Suppressing the lint only works if the lint runs without error, so this makes it impossible to consume outside of the pants repo right now (or at least, impossible in a lot of repos outside of the pants repo).

### Solution

- Revert pantsbuild#7286.

### Result

This will be unreverted asap when the above issues are investigated and fixed.

contrib/python/src/python/pants/contrib/python/checks/checker/BUILD

@@ -10,7 +10,6 @@ python_library(
     }
   ),
   dependencies=[
-    '3rdparty/python:asttokens',
     '3rdparty/python:future',
     '3rdparty/python:pycodestyle',
     '3rdparty/python:pyflakes',

contrib/python/src/python/pants/contrib/python/checks/checker/checker.py

@@ -17,8 +17,6 @@
 from pants.contrib.python.checks.checker.except_statements import ExceptStatements
 from pants.contrib.python.checks.checker.file_excluder import FileExcluder
 from pants.contrib.python.checks.checker.future_compatibility import FutureCompatibility
-from pants.contrib.python.checks.checker.implicit_string_concatenation import \
-  ImplicitStringConcatenation
 from pants.contrib.python.checks.checker.import_order import ImportOrder
 from pants.contrib.python.checks.checker.indentation import Indentation
 from pants.contrib.python.checks.checker.missing_contextmanager import MissingContextManager
@@ -134,7 +132,6 @@ def plugins():
     ConstantLogic,
     ExceptStatements,
     FutureCompatibility,
-    ImplicitStringConcatenation,
     ImportOrder,
     Indentation,
     MissingContextManager,

contrib/python/src/python/pants/contrib/python/checks/checker/common.py

@@ -12,7 +12,6 @@
 import textwrap
 import tokenize
 
-import asttokens
 import six
 
 
@@ -106,7 +105,6 @@ def _remove_coding_header(cls, blob):
   def __init__(self, blob, tree, root, filename):
     self._blob = self._remove_coding_header(blob)
     self.tree = tree
-    self.tokenized_file_body = asttokens.ASTTokens(self._blob, tree=self.tree, filename=filename)
     self.lines = OffByOneList(self._blob.decode('utf-8').split('\n'))
     self._root = root
     self.filename = filename

pants.ini

@@ -242,9 +242,6 @@ configuration: %(pants_supportdir)s/checkstyle/coding_style.xml
 [lint.google-java-format]
 skip: True
 
-[lint.pythonstyle]
-suppress: %(pants_supportdir)s/checkstyle/python_suppressions.txt
-
 [lint.python-eval]
 # After we fix the cycles from the engine refactor we should re-enable this.
 # https://github.com/pantsbuild/pants/issues/4601