buildkite: Replace wait step with explicit dependencies

This way, if the x86 build is faster than the ARM build, the x86 tests
can start running while the ARM ones are still blocked.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

.buildkite/common.py

@@ -261,7 +261,6 @@ def __init__(self, with_build_step=True, **kwargs):
             self.build_group_per_arch(
                 "🏗️ Build", build_cmds, decorate=False, key_prefix="build"
             )
-            self.steps += ["wait"]
         else:
             self.shared_build = None
 
@@ -297,6 +296,10 @@ def _adapt_group(self, group):
 
         for step in group["steps"]:
             step["command"] = prepend + step["command"]
+            if self.shared_build is not None:
+                step["depends_on"] = (
+                    "build_" + DEFAULT_INSTANCES[step["agents"]["instance"]]
+                )
         return group
 
     def build_group(self, *args, **kwargs):