Don't use cache because it's not yet initialized. Also, perform
safety checks only if state reset wasn't yet started. These fixes
alloww to solve the following problem while recovering from
interrupted state reset:
```
anna@kiwi:~/Documents/GitProjects/nspcc-dev/neo-go$ ./bin/neo-go db reset -t --height 83000
2022-11-20T15:51:31.431+0300 INFO MaxValidUntilBlockIncrement is not set or wrong, using default value {"MaxValidUntilBlockIncrement": 5760}
2022-11-20T15:51:31.434+0300 INFO restoring blockchain {"version": "0.2.6"}
failed to create Blockchain instance: could not initialize blockchain: current block height is 0, can't reset state to height 83000
```
283da8f599