6f6514a080 Correct units for "-dbcache" and "-prune" (Hennadii Stepanov)
Pull request description:
Actually, all `dbcache`-related values in the code are measured in MiB (not in megabytes, MB) or in bytes (e.g., `nTotalCache`).
See: https://github.com/bitcoin/bitcoin/blob/master/src/txdb.hba8c8b2227/src/init.cpp (L1405-L1424)
Also, "-prune" is fixed:
1. The GUI values in GB are translated to the node values in MiB correctly.
2. The maximum of the "prune" `QSpinBox` is not limited by default value of 99 (GB).
Fix: #15106
Tree-SHA512: 151ec43b31b1074db8b345fedb1dcc10bde225899a5296bfc183f57e1553d13ac27db8db100226646769ad03c9fcab29d88763065a471757c6c41ac51108459d