test: Avoid use of install with NFS

Running the Runtime tests in CI with NFS enabled currently fails because
'install' reports a permission error when trying to change permissions
of cilium.conf.ginkgo. This commit switches 'install' for 'chmod' which
works fine.

The reason for this error is that 'install' relies on the fsetxattr(2)
system call to change the permissions and, as pointed by Quentin, there
is no support for Extended File Attributes in NFS [1]. 'install'
therefore fails whereas 'chmod', which relies on fchmodat(2) works fine.

That bug wasn't found when running the Runtime test with NFS locally
because, for local tests, a different implementation of
RenderTemplateToFile() is used, one that does not rely on 'install'.

1 - https://tools.ietf.org/html/rfc8276
Signed-off-by: Paul Chaignon <paul@cilium.io>

test/helpers/node.go

@@ -334,10 +334,16 @@ func (s *SSHMeta) RenderTemplateToFile(filename string, tmplt string, perm os.Fi
 		return err
 	}
 
-	cmd := fmt.Sprintf("install -m %o <(echo '%s') %s\n", perm, content, filepath.Join(s.basePath, filename))
+	dst := filepath.Join(s.basePath, filename)
+	cmd := fmt.Sprintf("echo '%s' > %s", content, dst)
 	res := s.Exec(cmd)
 	if !res.WasSuccessful() {
 		return fmt.Errorf("%s", res.CombineOutput())
 	}
+	cmd = fmt.Sprintf("chmod %o %s", perm, dst)
+	res = s.Exec(cmd)
+	if !res.WasSuccessful() {
+		return fmt.Errorf("%s", res.CombineOutput())
+	}
 	return nil
 }