RST-11203 Copy latched messages once per split with connection header

[nleblanc-lr]

Eliminates a nearly identical copy of latched messages that was missing the original connection header, causing them to publish as unlatched.

[ayrton04]

Sorry, why would we not keep the copy, but include the header so latching works?

[nleblanc-lr]

It's the same exact message being copied twice, just once without the header (so it ends up with a default unlatched header), then again with the header. This causes problems when copying the messages into another bag with rosbag python which keeps the first header it encounters for each topic and keeps reusing it, so it ends up reusing the one without the latching flag. This just gets rid of the first copy without the latching flag, but the same message is still copied in with the flag immediately after the if block I removed (same exact if block, same comments and everything, just with the original header, which I'm guessing was a merge error somewhere along the line).