replace background image (grpc-bg.svg) with a simple gradient

[dragonsinth]

#316

The background image (grpc-bg.svg) is significantly large in size (1.7MB). When embedded into servers with limited bandwidth, it consumes a significant portion of the available resources and results in slower load times.

Please consider replacing the existing image with a simpler pattern or opt for a plain color background.

Before:

After:

Any feedback on the exact color choices is welcome.
CC: @lqs

[dragonsinth]

CC: @jhump what was the story on that SVG anyway?

[jhump]

A little surprising that it is so large... I just lifted it from the grpc.io home page (which still uses it today). I didn't think too much about it beyond that. My bad.

[dragonsinth]

A little surprising that it is so large... I just lifted it from the grpc.io home page (which still uses it today). I didn't think too much about it beyond that. My bad.

No big deal, I'm surprised anyone ever noticed!