chore: do not use sentinel errors when unneeded

- main reason being it's a burden to always define sentinel errors at global scope, wrap them with `%w` instead of using a string directly
- only use sentinel errors when it has to be checked using `errors.Is`
- replace all usage of these sentinel errors in `fmt.Errorf` with direct strings that were in the sentinel error
- exclude the sentinel error definition requirement from .golangci.yml
- update unit tests to use ContainersError instead of ErrorIs so it stays as a "not a change detector test" without requiring a sentinel error

internal/storage/formatting.go

@@ -1,7 +1,6 @@
 package storage
 
 import (
-	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -15,8 +14,6 @@ func commaJoin(slice []string) string {
 	return strings.Join(slice, ", ")
 }
 
-var ErrNoServerFound = errors.New("no server found")
-
 func noServerFoundError(selection settings.ServerSelection) (err error) {
 	var messageParts []string
 
@@ -160,5 +157,5 @@ func noServerFoundError(selection settings.ServerSelection) (err error) {
 
 	message := "for " + strings.Join(messageParts, "; ")
 
-	return fmt.Errorf("%w: %s", ErrNoServerFound, message)
+	return fmt.Errorf("no server found: %s", message)
 }