translations: Fix external translations logic
translations: Fix external translations logic

- Don't try to remove non existing files (If the file doesn't exists
ex_result will contain an error message and fail.)

- Make sure git init doesn't fail (If ${TR_TRANSLATION_DIR} doesn't
exist, git init will fail.)

pmattern/liblxqt,lxde/liblxqt,lxde/liblxqt,pmattern/liblxqt