ci/iris: Cut the glk-deqp test coverage in half.

It's taking 13-14 minutes of deqp-runner time, not counting booting, or
the LAVA-side job getting being queued behind other jobs.  Well past our
10-minute runtime target, and we saw load on these boards causing the
queue to get quite long
(https://gitlab.freedesktop.org/mesa/mesa/-/issues/6409#note_1368750)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16359>

src/intel/ci/deqp-iris-glk.toml

@@ -8,7 +8,7 @@ deqp_args = [
     "--deqp-surface-type=pbuffer", "--deqp-visibility=hidden",
     "--deqp-gl-config-name=rgba8888d24s8ms0",
 ]
-fraction = 3
+fraction = 6
 version_check = "GL ES 3.2.*git"
 renderer_check = "GLK"
 
@@ -21,7 +21,7 @@ deqp_args = [
     "--deqp-surface-type=pbuffer", "--deqp-visibility=hidden",
     "--deqp-gl-config-name=rgba8888d24s8ms0",
 ]
-fraction = 4
+fraction = 8
 
 [[deqp]]
 deqp = "/deqp/modules/gles31/deqp-gles31"
@@ -32,7 +32,7 @@ deqp_args = [
     "--deqp-surface-type=pbuffer", "--deqp-visibility=hidden",
     "--deqp-gl-config-name=rgba8888d24s8ms0",
 ]
-fraction = 4
+fraction = 8
 
 # Note that KHR-GL3* test sets include all tests from the previous
 # version, so we only need to run one test list (unlike dEQP-GLES,
@@ -51,6 +51,7 @@ deqp_args = [
     "--deqp-surface-type=pbuffer", "--deqp-visibility=hidden",
     "--deqp-gl-config-name=rgba8888d24s8ms0",
 ]
+fraction = 2
 
 # 565-nozs
 [[deqp]]
@@ -63,6 +64,7 @@ deqp_args = [
     "--deqp-gl-config-name=rgb565d0s0ms0",
 ]
 prefix = "565-nozs-"
+fraction = 2
 
 [[deqp]]
 deqp = "/deqp/modules/gles31/deqp-gles31"
@@ -74,6 +76,7 @@ deqp_args = [
     "--deqp-gl-config-name=rgb565d0s0ms0",
 ]
 prefix = "565-nozs-"
+fraction = 2
 
 # multisample
 [[deqp]]
@@ -86,6 +89,7 @@ deqp_args = [
     "--deqp-gl-config-name=rgba8888d24s8ms4",
 ]
 prefix = "multisample-"
+fraction = 2
 
 [[deqp]]
 deqp = "/deqp/modules/gles31/deqp-gles31"
@@ -97,3 +101,4 @@ deqp_args = [
     "--deqp-gl-config-name=rgba8888d24s8ms4",
 ]
 prefix = "multisample-"
+fraction = 2