nir/loop_analyze: Fix inverted condition handling in iterations calculation

nir/loop_analyze: Fix inverted condition handling in iterations calculation

In the tagged commit, we stopped actually inverting the condition, and
instead relied on the "invert_cond" flag. But we missed a few places
where this flag should've been handled too.

Also, add a few more tests to make sure this won't regress in the future.

Fixes: 99a7a664 ("nir/loop_analyze: Change invert_cond instead of changing the condition")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10012
Signed-off-by: Sviatoslav Peleshko <sviatoslav.peleshko@globallogic.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26024>
(cherry picked from commit aa33ca0a52591961f8ae01dc253354462ed17c18)