Remove custom linter against v7

[Samze]

Description of the Change

v7 version of #2921

There appears to be have been a custom linter introduced a long time ago, this is currently failing when running make all with:

....
Running custom linters...
bash -c "go run bin/style/main.go api util"
api/shared/wrap_for_cf_on_k8s.go +99 type declaration certRoundTripper defined after a function declaration
api/shared/wrap_for_cf_on_k8s.go +104 method certRoundTripper.RoundTrip defined after function getCert
exit status 1
make: *** [custom-lint] Error 1

Instead of fixing the custom linter, lets just remove it and rely on golangci-lint

Why Is This PR Valuable?

Allows developers to do git clone && make on the repo.

How Urgent Is The Change?

Not urgent

[gururajsh]

LGTM

[gururajsh]

LGTM