UX revisions to drill down header

[ngraham76]

Description

• Removed the kebab menu icon button next to the output dropdown as we no longer need the Save function here - it's now been added to operator's output header as a Save for re-use button
• Added a 1px bottom border (surface-border-alt) to the operator drilldown headers - defined in our Figma designs, was missing

[mwdchang]

We need to clean up the callers so they no longer generate and send in "menu-items" unnecessarily.

[mwdchang]

TA3 operators likely needs a bit of design tweaks for removing these menu-item paradigms, as they are saving different types of asset or assets. See follow up in:

#4713