Set maxShaderAtomicCounters to zero when atomic operation is not
supported. Some cts tests will only check maxShaderAtomicCounters
instead of vertexPipelineStoresAndAtomics before run.

Test: dEQP-GLES31.functional.shaders.opaque_type_indexing.atomic_counter.*vertex
Bug: angleproject:5272
Change-Id: Iceb4fc13eb26548ccbfaa430501d88f5ba3dfcc3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2507280
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>