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/mod/load_linux.go

@@ -1,7 +1,6 @@
 package mod
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -14,15 +13,10 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-var (
-	ErrModuleInfoNotFound = errors.New("module info not found")
-	ErrCircularDependency = errors.New("circular dependency")
-)
-
 func initDependencies(path string, modulesInfo map[string]moduleInfo) (err error) {
 	info, ok := modulesInfo[path]
 	if !ok {
-		return fmt.Errorf("%w: %s", ErrModuleInfoNotFound, path)
+		return fmt.Errorf("module info not found: %s", path)
 	}
 
 	switch info.state {
@@ -30,8 +24,7 @@ func initDependencies(path string, modulesInfo map[string]moduleInfo) (err error
 	case loaded, builtin:
 		return nil
 	case loading:
-		return fmt.Errorf("%w: %s is already in the loading state",
-			ErrCircularDependency, path)
+		return fmt.Errorf("circular dependency: %s is already in the loading state", path)
 	}
 
 	info.state = loading