Disable low power ticker on STM32_L073RZ

Currently LPTIM is disabled on L073RZ by

    4bead92 Use the RTC for the low power ticker on L073RZ

to work around a hardware bug. But the latency of RTC is too
high (a few hundred microseconds), leading to lp_timeout
drift test failure.

For now, disable low power ticker on L073RZ altogether until
LPTIM is fixed and re-enabled.

Author: LDong-Arm

targets/targets.json

@@ -3352,6 +3352,7 @@
             "FLASH",
             "MPU"
         ],
+        "device_has_remove": ["LPTICKER"],
         "release_versions": ["2", "5"],
         "bootloader_supported": true,
         "device_name": "STM32L073RZ"