[fuzzer] remove nullgl fuzzer
[fuzzer] remove nullgl fuzzer

It has long been deprecated and was removed in

https://skia-review.googlesource.com/c/skia/+/203703

Bug: skia:
Change-Id: I3ba495110699ad482ec5610ccd4bf169d1bf6caa
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/204080
Reviewed-by: Robert Phillips <95e8ac5504948c7bf91b22c16a8dbb7ae7c66bfd@google.com>
Commit-Queue: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>

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