Remove TODO for using `SkyKeyComputeState` in the Blaze-on-Skyframe codebase.

All of the heavy-hitter beneficiaries have already been rewritten:
* https://github.com/bazelbuild/bazel/commit/c68908ff3f916f07a005f425fe83000fb683b225: `PackageFunction`
* https://github.com/bazelbuild/bazel/commit/f40d0864f256d5df948c9efa56bc480b0943a56a: `PackageLookupFunction`
* https://github.com/bazelbuild/bazel/commit/6d695a1093bda302e0288b6b8786b9ef8ff44891: `ActionExecutionFunction`
* https://github.com/bazelbuild/bazel/commit/85e43800dfb7101c953748e08503d7d9b2fdf64c: `ConfiguredTargetFunction` and `AspectFunction`

PiperOrigin-RevId: 419957878

src/main/java/com/google/devtools/build/skyframe/SkyFunction.java

diff --git a/src/main/java/com/google/devtools/build/skyframe/SkyFunction.java b/src/main/java/com/google/devtools/build/skyframe/SkyFunction.java
index 4a9063e..0ce26e51 100644
--- a/src/main/java/com/google/devtools/build/skyframe/SkyFunction.java
+++ b/src/main/java/com/google/devtools/build/skyframe/SkyFunction.java
@@ -526,9 +526,6 @@
      * use the {@code stateSupplier}. It's important that Skyframe do this because {@link Restart}
      * indicates that work should be redone, and so it'd be wrong to reuse work from the previous
      * {@link #compute} call.
-     *
-     * <p>TODO(b/209701268): Reimplement Blaze-on-Skyframe SkyFunctions that would benefit from this
-     * sort of optimization.
      */
     <T extends SkyKeyComputeState> T getState(Supplier<T> stateSupplier);
   }