Drawing: Limit scale of rendered annotationview image

[frosty]

Improves wordpress-mobile/WordPress-iOS#14575, and fixes crashes that I was seeing.

UIGraphicsImageRendererFormat defaults to using the scale of the current screen, which was resulting in images 2 or 3x larger than their originals. This PR updates the renderer format to use a scale of 1.

To test

• Build and run
• Choose a device photo (I used the pink flowers) and draw something on top of it
• Ensure you have the Debug Navigator open in Xcode (showing CPU, memory, etc)
• When you tap Done, you should just see a small momentary increase in memory:

• Prior to this PR (you can test develop) you should see a more prolonged and much larger increase in memory. My simulator freezes up for a long time when this happens:

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[leandroalonso]

I don't think anything else will be added in 1.2.1, we can release it right away with this fix (without using a beta Pod). Wdyt?

[frosty]

Sure!