Organize local variables/references such that:

1. There is always a ChainstateManager reference before any LOCK(cs_main).
2. NodeContext references are used with Ensure*() functions introduced in previous commit where appropriate to avoid duplicate assertions.

This is a backport of core#21391 [12/14]
https://github.com/bitcoin/bitcoin/pull/21391/commits/6a3d1920209cded0dae52fb9070a3530d9a4e5fd

Depends on D11586

With clang and debug:
ninja all check-all