Ensure expected error in copytexsubimage2d_incomplete_framebuffer

Ensure expected error in copytexsubimage2d_incomplete_framebuffer

The GLES2 version of the copytexsubimage2d_incomplete_framebuffer test could
potentially throw INVALID_OPERATION instead of expected INVALID_FRAMEBUFFER_OPERATION
due to the cubemap texture not being defined by a previous TexImage2D.
This change re-uses the GLES3 version of the same test and ensures that
INVALID_FRAMEBUFFER_OPERATION is thrown.

Affects:
dEQP-GLES2.functional.negative_api.texture.copytexsubimage2d_incomplete_framebuffer

Change-Id: I7b3f770ff31c73d770a53f6b6bdae3ea4a37b63a
Components: AOSP
Google bug: 37497541

(cherry picked from commit 89bb39d24906bebd4e506f534e7336ffffec780b)