Remove old linux-chromeos bots from buildbucket and milo.

All of these were either renamed, or removed a while ago.

R=martiniss, jbudorick

Bug: 902468
Change-Id: I8f880c8b63fbbffca985eeef2ed273a75dff5d2a
Reviewed-on: https://chromium-review.googlesource.com/c/1321732Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605913}

infra/config/global/cr-buildbucket.cfg

@@ -3033,16 +3033,11 @@ buckets {
       mixins: "goma-j150"
       name: "linux_chromium_chromeos_asan_rel_ng"
     }
-    builders { mixins: "linux-try" name: "linux_chromium_chromeos_compile_dbg_ng" }
-    builders { mixins: "linux-try" name: "linux_chromium_chromeos_compile_rel_ng" }
-    builders { mixins: "linux-try" name: "linux_chromium_chromeos_dbg_ng" }
     builders {
       mixins: "linux-try"
       mixins: "goma-j150"
       name: "linux_chromium_chromeos_msan_rel_ng"
     }
-    builders { mixins: "linux-try" name: "linux_chromium_chromeos_ozone_rel_ng" }
-    builders { mixins: "linux-try" name: "linux_chromium_chromeos_rel_ng" }
     builders {
       name: "linux_chromium_clobber_deterministic",
       mixins: "linux-try"

infra/config/global/luci-milo.cfg

@@ -4854,24 +4854,9 @@ consoles {
   builders {
     name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_asan_rel_ng"
   }
-  builders {
-    name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_compile_dbg_ng"
-  }
-  builders {
-    name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_compile_rel_ng"
-  }
-  builders {
-    name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_dbg_ng"
-  }
   builders {
     name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_msan_rel_ng"
   }
-  builders {
-    name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_ozone_rel_ng"
-  }
-  builders {
-    name: "buildbucket/luci.chromium.try/linux_chromium_chromeos_rel_ng"
-  }
   builders {
     name: "buildbucket/luci.chromium.try/linux_chromium_clobber_deterministic"
   }