rustc: Remove special treatment for Freeze and NoFreeze

Fixes #12577
arena: Remove Freeze / NoFreeze
sync: Remove Freeze / NoFreeze
std::comm: Remove Freeze / NoFreeze
cell: Remove Freeze / NoFreeze
std: Remove the Freeze kind and the NoFreeze marker
test: Remove Freeze / NoFreeze from tests
doc: Remove Freeze / NoFreeze from docs