Reduce size of buffer used to prime the RenderEngine shader cache.

In local testing on Pixel 3XL the same shaders were produced when
compared to the old value and time spent in primeCache was reduced by ~200ms.

Test: atest librenderengine_test
Bug: 182658261
Change-Id: Id08db5822b05681876780225f92bf4601dc46c76
1 file changed