Remove fully inactivated linters

Currently golangci-lint fails with these errors:

ERRO [linters_context] golint: This linter is fully inactivated: it will not produce any reports.
ERRO [linters_context] interfacer: This linter is fully inactivated: it will not produce any reports.
ERRO [linters_context] maligned: This linter is fully inactivated: it will not produce any reports.

I could not find any docs explaining what "fully inactivated" mean, but
based this PR[1] it seems that these linters do nothing now. Removing
the linters fixes this issue without changing linting, as they did not
produce any report.

Looking in the linters docs[2] I did not find a replacement for
"interfacer" and "malinged" linters. "stylecheck" seems to be a
replacement for "golint", but we need to fix the code to enable it.

[1] golangci/golangci-lint#4436
[2] https://golangci-lint.run/usage/linters/

.golangci.yml

@@ -33,16 +33,13 @@ linters:
     #- gocyclo
     #- gofmt
     - goimports
-    - golint
     #- gomnd
     #- goprintffuncname
     #- gosec
     - gosimple
     - govet
     - ineffassign
-    - interfacer
     #- lll
-    - maligned
     - megacheck
     #- misspell
     #- nakedret