mac-videotoolbox: Don't manually override color space

[gxalpha]

Description

This was done to work around an issue in 2015 which does not appear to exist anymore in 2022. Thus, remove it to remove complexity, especially if we want to explicitly add HDR support (even though that already mostly works).

Motivation and Context

Less unnecessary code is better.

How Has This Been Tested?

macOS 13 Confirmed with CVBufferCopyAttachments that all of the attributes are already correctly set on the buffer.

Tested with H.264 Software, H.264 Hardware, and HEVC Hardware encoders.

Types of changes

• Code cleanup (non-breaking change which makes code smaller or more readable)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [x] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.

[gxalpha]

Closing. While these are indeed set usually, it appears that when some color formats are selected they might not be (For example it's set for NV12, but not when switching to P010 it isn't). Unsure why the color format would play a role here but that's how it is. Sucks that we have to carry this code but looks like it might be unavoidable. Sorry for wasting your time @PatTheMav, this is something I only noticed now.