Auto merge of #16176 - servo:jdm-patch-1, r=mbrubeck

Halve number of processes for test runs.

Let's see if this makes the intermittent failure situation improve!

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etc/ci/buildbot_steps.yml

@@ -59,13 +59,13 @@ linux-dev:
 linux-rel-wpt:
   - ./mach build --release --with-debug-assertions
   - ./mach test-wpt-failure
-  - ./mach test-wpt --release --processes 24 --log-raw test-wpt.log --log-errorsummary wpt-errorsummary.log --always-succeed
+  - ./mach test-wpt --release --processes 12 --log-raw test-wpt.log --log-errorsummary wpt-errorsummary.log --always-succeed
   - ./mach filter-intermittents wpt-errorsummary.log --log-intermittents intermittents.log --log-filteredsummary filtered-wpt-errorsummary.log --use-tracker
-  - ./mach test-wpt --release --binary-arg=--multiprocess --processes 24 --log-raw test-wpt-mp.log --log-errorsummary wpt-mp-errorsummary.log eventsource
+  - ./mach test-wpt --release --binary-arg=--multiprocess --processes 12 --log-raw test-wpt-mp.log --log-errorsummary wpt-mp-errorsummary.log eventsource
 
 linux-rel-css:
   - ./mach build --release --with-debug-assertions
-  - ./mach test-css --release --processes 16 --log-raw test-css.log --log-errorsummary css-errorsummary.log --always-succeed
+  - ./mach test-css --release --processes 8 --log-raw test-css.log --log-errorsummary css-errorsummary.log --always-succeed
   - ./mach filter-intermittents css-errorsummary.log --log-intermittents intermittents.log --log-filteredsummary filtered-css-errorsummary.log --use-tracker
   - ./mach build-cef --release --with-debug-assertions
   - ./mach build-geckolib --release