enable full linter across the codebase (#9620)

enable linter using golangci-lint across
codebase to run a bunch of linters together,
we shall enable new linters as we fix more
things the codebase.

This PR fixes the first stage of this
cleanup.

pkg/s3select/csv/args.go

@@ -26,9 +26,8 @@ import (
 )
 
 const (
-	none   = "none"
-	use    = "use"
-	ignore = "ignore"
+	none = "none"
+	use  = "use"
 
 	defaultRecordDelimiter      = "\n"
 	defaultFieldDelimiter       = ","
@@ -36,7 +35,6 @@ const (
 	defaultQuoteEscapeCharacter = `"`
 	defaultCommentCharacter     = "#"
 
-	always   = "always"
 	asneeded = "asneeded"
 )