Use large -j for slow win7_chromium_rel_ng compile step

This is for some slow tryjob due to long compile step in win7_chromium_rel_ng builder

examples from last 1 day
5384s https://ci.chromium.org/b/8943206699896945232
4334s https://ci.chromium.org/b/8943216691368144464
3743s https://ci.chromium.org/b/8943167746216898688
3628s https://ci.chromium.org/b/8943196039037892016

Bug: 804251
Change-Id: I5ae7a42e38aa143975034ee2da9b1f377feac7d3
Reviewed-on: https://chromium-review.googlesource.com/1109605Reviewed-by: Erik Staab <estaab@chromium.org>
Reviewed-by: Fumitoshi Ukai <ukai@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569180}

infra/config/global/cr-buildbucket.cfg

@@ -2582,7 +2582,11 @@ buckets {
     builders { mixins: "win-try" name: "win10_chromium_x64_rel_ng" }
     builders { mixins: "win-try" name: "win10_chromium_x64_rel_ng_exp" }
     builders { mixins: "win-try" mixins: "gn_upload" name: "win8_chromium_gn_upload" }
-    builders { mixins: "win-try" name: "win7_chromium_rel_ng" }
+    builders {
+      mixins: "win-try"
+      mixins: "goma-j150"
+      name: "win7_chromium_rel_ng"
+    }
     builders { mixins: "win-try" name: "win7_chromium_rel_loc_exp" }
     builders { mixins: "win-try" name: "win-annotator-rel" }
     builders { mixins: "win-try" name: "win-jumbo-rel" }