CI (Buildkite): use a consistent naming scheme for labels, keys, and commit statuses (#41543)

(cherry picked from commit ffc340c)

Author: DilumAluthge

.buildkite/embedding.yml

@@ -8,8 +8,8 @@ agents:
   os: "linux"
 
 steps:
-  - label: "Run embedding tests"
-    key: embedding
+  - label: "embedding"
+    key: "embedding"
     plugins:
       - JuliaCI/julia#v1:
           version: 1.6

.buildkite/llvm_passes.yml

@@ -9,7 +9,7 @@ agents:
 
 steps:
   - label: "analyzegc"
-    key: analyzegc
+    key: "analyzegc"
     plugins:
       - JuliaCI/julia#v1:
           version: 1.6
@@ -31,7 +31,7 @@ steps:
           context: "analyzegc"
 
   - label: "llvmpasses"
-    key: llvmpasses
+    key: "llvmpasses"
     plugins:
       - JuliaCI/julia#v1:
           version: 1.6
@@ -52,4 +52,4 @@ steps:
     timeout_in_minutes: 60
     notify:
       - github_commit_status:
-          context: "llvm passes"
+          context: "llvmpasses"

.buildkite/whitespace.yml

@@ -8,8 +8,8 @@ agents:
   os: "linux"
 
 steps:
-  - label: "Check whitespace"
-    key: whitespace
+  - label: "whitespace"
+    key: "whitespace"
     plugins:
       - JuliaCI/julia#v1:
           version: 1.6