Remove unnecassary calls to filepath.Join (go-gitea#17608)

- Partialy resolvess go-gitea#17596
- Resolves `badCall` errors from go-critic `badCall: suspicious Join on
1 argument`
- When only 1 argument is passed into `filepath.Join`, it won't do
anything special other than `filepath.Clean(...)` will be applied over
it.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>

modules/repository/adopt.go

@@ -154,7 +154,7 @@ func ListUnadoptedRepositories(query string, opts *db.ListOptions) ([]string, in
 	count := 0
 
 	// We're going to iterate by pagesize.
-	root := filepath.Join(setting.RepoRootPath)
+	root := filepath.Clean(setting.RepoRootPath)
 	if err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return err

routers/web/user/setting/adopt.go

@@ -27,7 +27,7 @@ func AdoptOrDeleteRepository(ctx *context.Context) {
 	action := ctx.FormString("action")
 
 	ctxUser := ctx.User
-	root := filepath.Join(models.UserPath(ctxUser.LowerName))
+	root := models.UserPath(ctxUser.LowerName)
 
 	// check not a repo
 	has, err := models.IsRepositoryExist(ctxUser, dir)

routers/web/user/setting/profile.go

@@ -250,7 +250,7 @@ func Repos(ctx *context.Context) {
 		repoNames := make([]string, 0, setting.UI.Admin.UserPagingNum)
 		repos := map[string]*models.Repository{}
 		// We're going to iterate by pagesize.
-		root := filepath.Join(models.UserPath(ctxUser.Name))
+		root := models.UserPath(ctxUser.Name)
 		if err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 			if err != nil {
 				if os.IsNotExist(err) {

services/pull/merge.go

@@ -275,8 +275,8 @@ func rawMerge(pr *models.PullRequest, doer *models.User, mergeStyle models.Merge
 					filepath.Join(tmpBasePath, ".git", "rebase-merge", "stopped-sha"),     // Git >= 2.26
 				}
 				for _, failingCommitPath := range failingCommitPaths {
-					if _, statErr := os.Stat(filepath.Join(failingCommitPath)); statErr == nil {
-						commitShaBytes, readErr := os.ReadFile(filepath.Join(failingCommitPath))
+					if _, statErr := os.Stat(failingCommitPath); statErr == nil {
+						commitShaBytes, readErr := os.ReadFile(failingCommitPath)
 						if readErr != nil {
 							// Abandon this attempt to handle the error
 							log.Error("git rebase staging on to base [%s:%s -> %s:%s]: %v\n%s\n%s", pr.HeadRepo.FullName(), pr.HeadBranch, pr.BaseRepo.FullName(), pr.BaseBranch, err, outbuf.String(), errbuf.String())