Resolve lint issues when running flake8

[parthea]

There are several failures when running flake8. This tracking bug was created as a follow up to ensure that all lint issues are addressed.

gapic-generator-python/.flake8

Lines 3 to 39 in a165ff3

	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E123, E124
	# Closing bracket mismatches opening bracket's line.
	# This works poorly with type annotations in method declarations.
	E123, E124
	# Line over-indented for visual indent.
	# This works poorly with type annotations in method declarations.
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E126, E128, E131
	E126, E128, E131
	# Line break after binary operator.
	# This catches line breaks after "and" / "or" as a means of breaking up
	# long if statements, which PEP 8 explicitly encourages.
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): W504
	W504
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E203
	E203
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E501
	E501
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E712
	E712
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E711
	E711
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E722
	E722
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): E741
	E741
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): F401
	F401
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): F541
	F541
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): F841
	F841
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): F811
	F811
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): W503
	W503
	# TODO(https://github.com/googleapis/gapic-generator-python/issues/2333): W291
	W291

[parthea]

Also see these lines where we're excluding linting on generated code

gapic-generator-python/gapic/templates/.flake8.j2

Lines 23 to 25 in 30cd1a4

	**/gapic/**
	**/services/**
	**/types/**