egl: Stop requiring EXT_create_context_robustness for EGL 1.5

For the similar commit c738cfe8 a review comment was:
> The EGL 1.5 changelog says that it incorporates the 3D texture
> extension's methods, but does not seem to require that they succeed.

The same could be said for Reset Notification Strategy and Robust Buffer
Access as implementations seem to be explicitely allowed to not succeed.
The EGL 1.5 spec says:
> "An EGL_BAD_MATCH error is generated if an OpenGL or OpenGL ES
> context is requested with robust buffer access and with a
> specified reset notification behavior, and the implementation
> does not support that behavior."

As we do return these errors accordingly during context creation, stop
requiring drivers to implement successfull creation of robust contexts,
as indicated by the extension.

Signed-off-by: Robert Mader <robert.mader@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30764>

src/egl/main/eglapi.c

@@ -654,7 +654,6 @@ _eglComputeVersion(_EGLDisplay *disp)
        disp->Extensions.KHR_gl_texture_cubemap_image &&
        disp->Extensions.KHR_gl_renderbuffer_image &&
        disp->Extensions.KHR_create_context &&
-       disp->Extensions.EXT_create_context_robustness &&
        disp->Extensions.KHR_get_all_proc_addresses &&
        disp->Extensions.KHR_gl_colorspace &&
        disp->Extensions.KHR_surfaceless_context)