[presubmit] Disable linter check for alpha-sorted includes.

The linter (i.e. cpplint.py) no longer needs to check for alpha-sorted
include directives because our source formatting (i.e. clang-format)
will take care of this by now. This is the current default configuration
of the underlying linter anyways.

Note that the two tools disagree about the correct ordering about files
containing dash characters. The ordering suggested by the formatter is
more natural. Having the formatter trigger linter errors is not a good
situation to be in.

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/1822003002

Cr-Commit-Position: refs/heads/master@{#34985}

tools/presubmit.py

@@ -58,7 +58,6 @@ from testrunner.local import utils
 
 LINT_RULES = """
 -build/header_guard
-+build/include_alpha
 -build/include_what_you_use
 -build/namespaces
 -readability/check