CI (Buildkite): move the asan job from "experimental" to "main"

Author: DilumAluthge

.buildkite/pipelines/experimental/launch_unsigned_builders.yml

@@ -1,6 +1,6 @@
 steps:
   - label: ":buildkite: Launch unsigned pipelines"
     commands: |
-      buildkite-agent pipeline upload .buildkite/pipelines/experimental/misc/sanitizers.yml
+      true
     agents:
       queue: julia

.buildkite/pipelines/main/launch_unsigned_builders.yml

@@ -22,6 +22,7 @@ steps:
       buildkite-agent pipeline upload .buildkite/pipelines/main/misc/doctest.yml
       buildkite-agent pipeline upload .buildkite/pipelines/main/misc/embedding.yml
       buildkite-agent pipeline upload .buildkite/pipelines/main/misc/llvmpasses.yml
+      buildkite-agent pipeline upload .buildkite/pipelines/main/misc/sanitizers.yml
 
       # Launch all of the platform builders.
       bash .buildkite/pipelines/main/platforms/platforms.sh package_linux

.buildkite/pipelines/experimental/misc/sanitizers.yml renamed to .buildkite/pipelines/main/misc/sanitizers.yml

@@ -16,9 +16,6 @@ steps:
           gid: 1000
           workspaces:
             - "/cache/repos:/cache/repos"
-      # `contrib/check-asan.jl` needs a `julia` binary inside the inner sandbox:
-      - JuliaCI/julia#v1:
-          version: 1.6
     timeout_in_minutes: 120
     commands: |
       echo "--- Build julia-debug with ASAN"