Simplify fmt-check (#21458)

`fmt-check` now simply does `fmt` before and relies on `git diff` like
other checks like 'tidy-check' already do, so we can remove the argument
in the tool that handles printing changed files.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

.golangci.yml

@@ -12,7 +12,6 @@ linters:
     - dupl
     #- gocyclo # The cyclomatic complexety of a lot of functions is too high, we should refactor those another time.
     - gofmt
-    - misspell
     - gocritic
     - bidichk
     - ineffassign
@@ -148,9 +147,6 @@ issues:
     - path: models/issue_comment_list.go
       linters:
         - dupl
-    - linters:
-        - misspell
-      text: '`Unknwon` is a misspelling of `Unknown`'
     - path: models/update.go
       linters:
         - unused