What is the ruling on saying: "O Allah, I ask You that I never disobey You," or "O Allah, I ask You that I never commit a specific sin," and is this considered an transgression in supplication?

There is no transgression in the two supplications mentioned. They are a plea to God to protect you and guard you from disobeying Him. Umar ibn al-Khattab used to supplicate: "O Allah, protect me with Your rope, and grant me from Your bounty, and make me preserve Your command." Al-Suyuti permitted asking for protection from sins, explaining that infallibility is obligatory for prophets and angels, and permissible for others, and that proper etiquette dictates asking for preservation (hifz) rather than infallibility (ismah) for those other than prophets. This may be what is intended here.