[bugfix] cleanup ReplaceRobot.treat(), move statements outside the loop

• test isTextExcepted() for the original_text instead for the modified
• replace text only once instead over and over again
• add the optionated category outside the loop
• leave treat method after opening the browser

Bug: T363047
Change-Id: I57417bfaf22627a76cc61db5ba58c4c35e3d77fd