[test] Adjust shards on slow bots

No-Try: true
Bug: v8:12748
Change-Id: Ide093521c9d1c5927c5c1bea30a6f7689486f079
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3562983
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79732}

infra/testing/builders.pyl

@@ -280,11 +280,11 @@
       'os': 'Ubuntu-18.04',
     },
     'tests': [
-      {'name': 'mjsunit_sp_frame_access'},
-      {'name': 'mozilla', 'shards': 2},
+      {'name': 'mjsunit_sp_frame_access', 'shards': 3},
+      {'name': 'mozilla', 'shards': 3},
       {'name': 'test262', 'variant': 'default', 'shards': 2},
-      {'name': 'v8testing', 'shards': 8},
-      {'name': 'v8testing', 'variant': 'extra', 'shards': 7},
+      {'name': 'v8testing', 'shards': 10},
+      {'name': 'v8testing', 'variant': 'extra', 'shards': 10},
     ],
   },
   'v8_linux_arm_lite_rel_ng_triggered': {
@@ -1813,8 +1813,8 @@
       'os': 'Ubuntu-18.04',
     },
     'tests': [
-      {'name': 'mjsunit_sp_frame_access', 'shards': 6},
-      {'name': 'mozilla', 'shards': 6},
+      {'name': 'mjsunit_sp_frame_access', 'shards': 3},
+      {'name': 'mozilla', 'shards': 3},
       {'name': 'test262', 'variant': 'default', 'shards': 2},
       {'name': 'v8testing', 'shards': 10},
       {'name': 'v8testing', 'variant': 'extra', 'shards': 10},