🐛 Fix EZBoard V2 Environment for OpenBLT (#23659)

ini/stm32f4.ini

 extends             = stm32_variant
 board               = genericSTM32F405RG
 board_build.variant = MARLIN_TH3D_EZBOARD_V2
+board_build.encrypt = firmware.bin
 board_build.offset  = 0xC000
 board_upload.offset_address = 0x0800C000
 build_flags         = ${stm32_variant.build_flags} -DHSE_VALUE=12000000U -O0
 debug_tool          = stlink
 upload_protocol     = stlink
+extra_scripts       = ${stm32_variant.extra_scripts}
+                      buildroot/share/PlatformIO/scripts/openblt.py
 
 #
 # BOARD_MKS_ROBIN_NANO_V1_3_F4