[infra] Avoid timeouts in CreateDockerImage_Skia_WASM_Release

Change-Id: Ia167a4ed2697374d140d989134ec6ac66b01f023
Bug: skia:13128
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/528696
Reviewed-by: Joe Gregorio <jcgregorio@google.com>

docker/skia-wasm-release/Dockerfile

@@ -10,6 +10,8 @@ RUN cd /tmp \
 
 ENV PATH=${PATH}:/tmp/depot_tools
 
+# See skbug.com/13128
+ENV DEPOT_TOOLS_UPDATE=0
 # Checkout Skia using fetch from depot_tools
 RUN mkdir -p /tmp/skia \
   && cd /tmp/skia \