Code cleanup (#9992)

* Value assigned to a variable is never read before being overwritten

* The result of append is not used anywhere

* Suspicious assignment of range-loop vars detected

* Unused method receiver detected

* Revert "Auxiliary commit to revert individual files from 54edcb445484a2e5d79612e19af8e949b8861253"

This reverts commit bbd1e1beabf7b0c5cfc4f514dcc820062ad6c063.

* Method modifies receiver

* Fix test

* Duplicate imports detected

* Incorrectly formatted error string

* Types of function parameters can be combined

* One more "Unused method receiver detected"

* Unused parameter detected in function

cmd/password_reader.go

@@ -16,7 +16,7 @@ type StdInPasswordReader struct {
 }
 
 // ReadPassword reads a password from stdin.
-func (pr StdInPasswordReader) ReadPassword() (string, error) {
+func (_ StdInPasswordReader) ReadPassword() (string, error) {
 	pwd, err := terminal.ReadPassword(int(os.Stdin.Fd()))
 	return string(pwd), err
 }