Regression of brightness_gamma bug in latest Preview/Beta

In 1.20.60.22 preview/beta, MCPE-167836 was fixed, allowing resource packs to modify the "brightness_gamma" property of any block. The issue reappeared in the following 1.20.60.23 preview.

As it was not listed in the changelog, this regression is likely unintentional. When MCPE-167836 is fixed once again, MCPE-177356 should also be fixed to maintain snow and nether brick visual cohesion.