options: Remove parsing --verbose from the configuration file

The `--verbose` option is only used by `flake8`, itself,` when parsing
and handling preliminary options.  After parsing and merging options
from the configuration file, there is no other behavioral impact to the
core of `flake8`.  In other words, setting `verbose = ...` in a
configuration file doesn't change the logging verbosity.

While the `FileProcessor` does expose a `verbose` attribute, obtained
from the parsed options, the verbosity of the core of `flake8` should be
consistent with how a plugin may respond to the attribute's value.

src/flake8/main/options.py

@@ -48,7 +48,6 @@ def register_default_options(option_manager):
         "--verbose",
         default=0,
         action="count",
-        parse_from_config=True,
         help="Print more information about what is happening in flake8."
         " This option is repeatable and will increase verbosity each "
         "time it is repeated.",