1b51616f2e test: improve rogue calls in mining functions (i-am-yuvi)
Pull request description:
#31403 follow-up, see [comment](https://github.com/bitcoin/bitcoin/pull/31403#pullrequestreview-2498806354)
- Rename `invalid_call` parameter to `called_by_framework` in `generateblock`, `generatetoaddress` and `generatetodescriptor` mining methods to better express its intended usage.
- Add explicit assertion message clarifying that these functions should only be called by TestFramework itself to maintain proper node synchronization.
ACKs for top commit:
maflcko:
lgtm ACK 1b51616f2e
achow101:
ACK 1b51616f2e
hodlinator:
re-ACK 1b51616f2e
Prabhat1308:
ACK [1b51616](1b51616f2e)
Tree-SHA512: 56832626fe54dcaa07dacb4f9c960c0a83fad3fb12272155114ac697856c59b7f44805e1152eddeec7a5e8f7daf487382dc01b5b9ae2e74b62b2df6bd1f81f77