run_dex2oat: remove FDE-specific code

run_dex2oat had special behavior when the device is running a minimal
framework for unlocking Full Disk Encryption (FDE), as indicated by the
vold.decrypt system property.  As FDE support was removed in Android 13
in favor of File Based Encryption (FBE), this code is no longer needed.

Bug: 208476087
Test: atest run_dex2oat_test
Change-Id: I2d7be81b0f4a9fc4378b01627708f53ea04455f2