gitlab-ci: Add three more dEQP-GLES31 tests to softpipe skips
These have randomly flipped lately, see e.g. https://gitlab.freedesktop.org/mesa/mesa/-/jobs/1620056 https://gitlab.freedesktop.org/daenzer/mesa/-/jobs/1621374 https://gitlab.freedesktop.org/daenzer/mesa/-/jobs/1622156
Edited by Michel Dänzer