CI, pytest: Add a test for sandbox without LTO

The primary motivation for having a sandbox without LTO build in CI is
to ensure that we don't have that option break. We now have the ability
to run tests of specific options being enabled/disabled, so drop the
parts of CI that build and test that configuration specifically and add
a build test instead. We still test that "NO_LTO=1" rather than editing
the config file works via the ftrace tests.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
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Changes in v5:
- Drop now incorrect worry about bisectability