Only precompile blur pipelines for the selected blur algorithm

Another approach could be to change
RuntimeEffectManager::getKnownRuntimeEffect(...) to be non-fatal when an
no valid SkRuntimeEffect is found, and use that to probe which
SkRuntimeEffects were prepared, and thus determine which
PrecompileSettings are relevant.

However, looking at the chosen BlurAlgorithm instead forces visibility
into this precompilation code when a new blur algorithm is added, and
also allows us to differentiate between scenarios of BlurAlgorithm::None
being chosen vs. a blur algorithm that just doesn't have precompilation
cases defined when it comes to logging.

Test: local logging to ensure correct pipelines are precompiled
Bug: b/432467687
Flag: com.android.graphics.surfaceflinger.flags.graphite_renderengine
Change-Id: Iad38541511b3ac139dc0ff6335cd0400e2bea74e