Vulkan: avoid disabling explicitlyCastMediumpFloatTo16Bit for venus We disabled it to work around below legacy skia cts: CtsSkQPTestCases org.skia.skqp.SkQPRunner#gles_gradient_many_stops The test no longer exists in newer skia cts. Meanwhile, we have to drop the workaround for other precision issue on Mali-G52. Bug: b/316474995 Test: dEQP-GLES2.functional.shaders.algorithm.rgb_to_hsl_vertex Change-Id: I18394595632d05657e96f8b9c9675b4dd959d92b Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5133372 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Auto-Submit: Yiwei Zhang <zzyiwei@chromium.org> Commit-Queue: Yiwei Zhang <zzyiwei@chromium.org>