Update Toolbar margin and remove hide button

[makeavish]

https://github.com/SigNoz/signoz/issues/4771#issuecomment-2038642618

I'd also point out here once that the solution we arrived at now was also due to a slight mischaracterization of the feedback we received from the users. Users wouldn't want to hide/unhide the toolbar often. User would want to see the data unhindered, which was blocked by the lack of bottom spacing 👀 (and the ideal solution was not a hide button, it was more bottom spacing)