Stop testing stable-v2.16.6

Author: cklin

.github/workflows/__go-tracing-autobuilder.yml

@@ -70,7 +70,7 @@ We typically release new minor versions of the CodeQL Action and Bundle when a n
 
 | Minimum CodeQL Action | Minimum CodeQL Bundle Version | GitHub Environment | Notes |
 |-----------------------|-------------------------------|--------------------|-------|
-| `v3.28.21`  | `2.20.7` | Enterprise Server 3.18 | |
+| `v3.28.21`  | `2.21.3` | Enterprise Server 3.18 | |
 | `v3.28.12`  | `2.20.7` | Enterprise Server 3.17 | |
 | `v3.28.6`  | `2.20.3` | Enterprise Server 3.16 | |
 | `v3.28.6`  | `2.20.3` | Enterprise Server 3.15 | |

.github/workflows/__go-tracing-custom-build-steps.yml

@@ -9,15 +9,15 @@
 # The default set of CodeQL Bundle versions to use for the PR checks.
 defaultTestVersions = [
     # The oldest supported CodeQL version. If bumping, update `CODEQL_MINIMUM_VERSION` in `codeql.ts`
-    "stable-v2.16.6",
-    # The last CodeQL release in the 2.17 series.
     "stable-v2.17.6",
     # The last CodeQL release in the 2.18 series.
     "stable-v2.18.4",
     # The last CodeQL release in the 2.19 series.
     "stable-v2.19.4",
     # The last CodeQL release in the 2.20 series.
     "stable-v2.20.7",
+    # The last CodeQL release in the 2.21 series.
+    "stable-v2.21.4",
     # The default version of CodeQL for Dotcom, as determined by feature flags.
     "default",
     # The version of CodeQL shipped with the Action in `defaults.json`. During the release process