TimTum_KermitTimTumcolor_bar_health_x under playerpanels_kv under TeamStatus inside of HudMatchStatus.resTimTum........
Sorry I probably shouldn't have used a picture with the engineer. I'm talking about the steam avatar picture, on the main menu for example:
It's blue on my hud right now, but on the previous screenshot another hud was able to make it white.
You can change the party member colors from the clientscheme or whatever the color schene is called in the hud, look for "PartyMember1" , "PartyMember2" etc
Also the "party" section of the dashboard is controlled by DashBoardPartyMember.res as well, just in case you want to edit it