flashy-a1713b0

relax the free RAM floor to 30M on wedge100

Summary:
See S697061 for context, 30_ensure_enough_free_ram requires 45M free before an upgrade. Recent wedge100 releases cannot
meet that outside a short window after boot, so the step exits 42 and the caller
reboots the device.

Test Plan:
Unit tests

  cd tools/flashy && ./scripts/run_unit_tests.sh
  162/162 unit tests passed

Build `openbmc.utils.flashy` ephemeral, pin it in ooberaser code
```
 diff --git a/fbcode/openbmc/erase/core/erase.py b/fbcode/openbmc/erase/core/erase.py
 --- a/fbcode/openbmc/erase/core/erase.py
+++ b/fbcode/openbmc/erase/core/erase.py
@@ -1046,6 +1046,10 @@
         self._logger.info("Preparing to run Flashy checks")
         flashy = Flashy(self._openbmc, self._logger)

+        # XXX LOCAL TESTING ONLY - DO NOT COMMIT
+        # Pin the flashy fbpkg instead of resolving openbmc.utils.flashy:DEFAULT
+        flashy.FBPKG_TAG = "fd431e7"
+
         # Get the current push image to flash to the device post-wipe
         image = obmc_versions.get_fbpkg_version(self.build_name)
         self._logger.info(f"Downloading {image} to flash to the device")
```

Run ooberaser locally using https://wiki.internalmeta.com/wiki/OpenBMC/OOBEraser_(aka_OpenBMC_Eraser)/Developer_Guide targeting a device running openbmc.image.wedge100:v2026.09.0:
```
 ./ooberaser --host rsw012-oob.p007.f01.prn6 --skip-wipe-certs --force --wait --tier local
```

While flashy is running, created a dummy file so mem free stayed on 30M on average, ensure flashy/wipe job succeeds

Differential Revision: D116460585

fbshipit-source-id: cd806016bab633340e9e4684fbeb0788319bac03