iris: Skip mi_builder init for indirect draws

iris: Skip mi_builder init for indirect draws

We only need it for indirect draws.

Improves performance on an i7-12700 and A770:

- Piglit's drawoverhead base case +150.639% +/- 2.86933% (n=15).
- gfxbench5 gl_driver2_off +19.7219% +/- 1.13778% (n=15)
- SPECviewperf2020 catiav5test1 +1.6831% +/- 0.552052% (n=10).

Cc: mesa-stable
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26806>
(cherry picked from commit 55c262898ae7188311c89a60e4ec0fbb67b7a95b)