Use a STR_ prefix for non-translated strings

Marlin/src/HAL/HAL_AVR/persistent_store_eeprom.cpp

Marlin/src/HAL/HAL_AVR/watchdog.cpp

Marlin/src/HAL/HAL_DUE/persistent_store_eeprom.cpp

Marlin/src/HAL/HAL_SAMD51/persistent_store_eeprom.cpp

Marlin/src/HAL/HAL_STM32/persistent_store_impl.cpp

Marlin/src/HAL/HAL_STM32F1/persistent_store_eeprom.cpp

Marlin/src/HAL/HAL_STM32_F4_F7/persistent_store_eeprom.cpp

Marlin/src/HAL/HAL_TEENSY31_32/persistent_store_impl.cpp

Marlin/src/HAL/HAL_TEENSY35_36/persistent_store_eeprom.cpp

Marlin/src/MarlinCore.cpp

Marlin/src/core/language.h

Marlin/src/core/serial.cpp

Marlin/src/feature/bltouch.cpp

Marlin/src/feature/pause.cpp

Marlin/src/feature/prusa_MMU2/mmu2.cpp

Marlin/src/feature/solenoid.cpp

Marlin/src/gcode/bedlevel/G42.cpp

Marlin/src/gcode/bedlevel/M420.cpp

Marlin/src/gcode/bedlevel/abl/M421.cpp

Marlin/src/gcode/bedlevel/mbl/M421.cpp