Optimise D2 pick icon in data-uri

I decoded the base64 and exported it into a png file, then I ran ImageOptim on it and re-encoded it to base64.

Before: 3774 bytes
After: 564 bytes

Gains: 85.1%
Optimise Android release message pattern
Optimise off target goals background
Add quotes around url
Merge pull request #4911 from guardian/d2-icon-optimise

Optimise data-uri PNGs