ci: disable the windows tests until the runner can be stabilized again
I've been getting a stream of errors from Marge today like:
FAILED: src/gallium/drivers/llvmpipe/lp_test_conv.exe link @src/gallium/drivers/llvmpipe/lp_test_conv.exe.rsp LINK : fatal error LNK1102: out of memory [1080/1141] Compiling C object src/gallium/frontends/wgl/945cc3d@@wgl@sta/stw_getprocaddress.c.obj