Remove `Repository.getFilesChanged` to fix Actions `paths` and `paths-ignore` filter (#23920)

Remove the misbehaving function and call
Repository.GetFilesChangedBetween instead.

Fixes #23919

---

~~_TODO_ test this~~ `Repository.getFilesChanged` seems to be only used
by Gitea Actions, but a similar function already exists

**Update** I tested this change and the issue is gone.

modules/git/commit.go

@@ -291,7 +291,7 @@ func (c *Commit) SearchCommits(opts SearchCommitsOptions) ([]*Commit, error) {
 
 // GetFilesChangedSinceCommit get all changed file names between pastCommit to current revision
 func (c *Commit) GetFilesChangedSinceCommit(pastCommit string) ([]string, error) {
-	return c.repo.getFilesChanged(pastCommit, c.ID.String())
+	return c.repo.GetFilesChangedBetween(pastCommit, c.ID.String())
 }
 
 // FileChangedSinceCommit Returns true if the file given has changed since the the past commit

modules/git/repo_commit.go

@@ -182,14 +182,6 @@ func (repo *Repository) searchCommits(id SHA1, opts SearchCommitsOptions) ([]*Co
 	return repo.parsePrettyFormatLogToList(bytes.TrimSuffix(stdout, []byte{'\n'}))
 }
 
-func (repo *Repository) getFilesChanged(id1, id2 string) ([]string, error) {
-	stdout, _, err := NewCommand(repo.Ctx, "diff", "--name-only").AddDynamicArguments(id1, id2).RunStdBytes(&RunOpts{Dir: repo.Path})
-	if err != nil {
-		return nil, err
-	}
-	return strings.Split(string(stdout), "\n"), nil
-}
-
 // FileChangedBetweenCommits Returns true if the file changed between commit IDs id1 and id2
 // You must ensure that id1 and id2 are valid commit ids.
 func (repo *Repository) FileChangedBetweenCommits(filename, id1, id2 string) (bool, error) {