Bug 1608390 - Run SpiderMonkey Windows 32 bit as Tier 2 only on mozilla-central, r=jmaher,sfink,aryx

Differential Revision: https://phabricator.services.mozilla.com/D61638

--HG--
extra : moz-landing-system : lando

taskcluster/ci/spidermonkey/windows.yml

@@ -33,9 +33,11 @@ sm-plain-win32/debug:
     treeherder:
         platform: windows2012-32/debug
         symbol: SM(p)
+        tier: 2
     run:
         spidermonkey-variant: plaindebug
         spidermonkey-platform: win32
+    run-on-projects: ['mozilla-central', 'try']
     fetches:
         toolchain:
             - win64-clang-cl
@@ -66,9 +68,11 @@ sm-plain-win32/opt:
     treeherder:
         platform: windows2012-32/opt
         symbol: SM(p)
+        tier: 2
     run:
         spidermonkey-variant: plain
         spidermonkey-platform: win32
+    run-on-projects: ['mozilla-central', 'try']
     fetches:
         toolchain:
             - win64-clang-cl
@@ -99,6 +103,7 @@ sm-compacting-win32/debug:
     treeherder:
         platform: windows2012-32/debug
         symbol: SM(cgc)
+        tier: 2
     run:
         spidermonkey-variant: compacting
         spidermonkey-platform: win32