Delete incorrect invalid map transform feedback subtest.

Delete incorrect invalid map transform feedback subtest.

The citation given in this test comes from the OpenGL man pages, which
are not authoritative.  The ES 3.2 and GL 4.x specifications say:

   "Effects of Mapping Buffers on Other GL Commands

    Any GL command which attempts to read from, write to, or change the
    state of a buffer object may generate an INVALID_OPERATION error if
    all or part of the buffer object is mapped. However, only commands
    which explicitly describe this error are required to do so. If an
    error is not generated, using such commands to perform invalid
    reads, writes, or state changes will have undefined results and may
    result in GL interruption or termination."

Importantly, it says "_may_ generate an INVALID_OPERATION error".  Some
drivers choose not to implement this to avoid the CPU overhead required
to enforce this optional restriction.

Affects:
- KHR-*.transform_feedback.api_errors_test

VK-GL-CTS issue: 765

Change-Id: I34ca78926fe0f311db096de98b71e0981ee91d53
Components: OpenGL