Clarify status of DEBUG_JBM_CMD_OPTION, VARIABLE_SPEED_DECODING

Both switches DEBUG_JBM_CMD_OPTION and VARIABLE_SPEED_DECODING are currently under the debugging section of options.h, but are currently active.

The status is not clear to me:

• Are they supposed to be active or not?
• What impact has switching them off (decoder output, CI testing)?
• What should we do with them for the source-code delivery?