Manual optimization of images/blogimages

Why is this change being made?

This MR optimizes all images in source/images/blogimages with ImageOptimize. https://imageoptim.com/mac

Directory size before optimization was 403.8 MB

Directory size after optimization is 377.5 MB

Savings is 26.3 MB

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

related https://gitlab.com/gitlab-com/marketing/web-analytics/issues/14

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what