Auto merge of #22459 - servo:tc-macos-wpt, r=jdm

Move macOS WPT chunk 1 (only) from Buildbot to Taskcluster

This is only one chunk at a time so that we don’t need to double the number of worker nor the cycle time during the migration.

A release build takes ~40 minutes which seems worrying, but this also happens (sometimes) on Buildbot. For example: https://build.servo.org/builders/mac-rel-wpt1/builds/10401

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/22459)
<!-- Reviewable:end -->

etc/ci/buildbot_steps.yml

@@ -5,18 +5,6 @@ env:
   SCCACHE_IDLE_TIMEOUT: "1200"
   GST_DEBUG: '3'
 
-mac-rel-wpt1:
-  - ./mach clean-nightlies --keep 3 --force
-  - ./mach clean-cargo-cache --keep 3 --force
-  - env PKG_CONFIG_PATH=/usr/local/opt/zlib/lib/pkgconfig ./mach build --release
-  - ./mach run -r -o output.png
-  - ./mach test-wpt-failure
-  - ./mach test-wpt --release --processes 4 --total-chunks 6 --this-chunk 1 --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 --tracker-api default --reporter-api default
-  - ./mach test-wpt --release --binary-arg=--multiprocess --processes 8 --log-raw test-wpt-mp.log --log-errorsummary wpt-mp-errorsummary.log eventsource
-  - ./mach test-wpt --release --product=servodriver --headless tests/wpt/mozilla/tests/mozilla/DOMParser.html tests/wpt/mozilla/tests/css/per_glyph_font_fallback_a.html tests/wpt/mozilla/tests/css/img_simple.html tests/wpt/mozilla/tests/mozilla/secure.https.html
-  - bash ./etc/ci/lockfile_changed.sh
-
 mac-rel-wpt2:
   - ./mach clean-nightlies --keep 3 --force
   - ./mach clean-cargo-cache --keep 3 --force
@@ -243,3 +231,4 @@ android: []
 android-x86: []
 linux-rel-wpt: []
 linux-rel-css: []
+mac-rel-wpt1: []