refactor: disable remaining fast node logic in mutable tree

[p0mvn]

Skip fast node removals when fast node is disabled to avoid any possibility of those removals being read, leading to inconsistent state between nodes that have fast nodes and the nodes that do not.

[faddat]

thank you from Notional and evmos

But really, fastnode has worked 100% of the time, and it's baroque to if wannagofast=false {allkinds of stuff} everywhere in the codebase.

seriously why would we kill art itself because some archives took a long time to upgrade?

they're archives, after all.

fastnode worked 100% of the time, until there was this zany idea we might not want to use it because multi-terabyte archive nodes with millions of accounts took a long time to upgrade....

[yihuang]

leading to inconsistent state between nodes that have fast nodes and the nodes that do not.

does this cause observable inconsistency, like app-hash mismatch, or just a preventive change?

[p0mvn]

leading to inconsistent state between nodes that have fast nodes and the nodes that do not.

does this cause observable inconsistency, like app-hash mismatch, or just a preventive change?

Just a preventive change