Expose 3.4-asan Ruby builds from ruby-dev-builder

**What does this PR do?**

This PR provides the final piece of the puzzle to fix #682: now that
ruby-dev-builder is building `3.4-asan` Rubies since
https://github.com/ruby/ruby-dev-builder/pull/15, we can make them
available for use.

**Motivation:**

At Datadog, we're using ASan builds to check for issues
[in our library](https://github.com/datadog/dd-trace-rb),
and having a `3.4-asan` build improves the experience of having
these checks be a required CI step. Using the ASan builds built from
ruby-head means our CI could break because of unrelated issues/changes
from ruby-head.

**Additional Notes:**

`yarn` was trying really hard to update a bunch of things, which
generated A LOT of diff noise. I've manually pared them down just
to the actual changes related to adding the new variant so the
diff makes a bit more sense.

**How to test the change?**

I've already tested this in
https://github.com/DataDog/dd-trace-rb/actions/runs/13392865620/job/37696781848
and it seems to be working fine!

ruby-builder-versions.json

@@ -14,7 +14,7 @@
     "3.2.0-preview1", "3.2.0-preview2", "3.2.0-preview3", "3.2.0-rc1", "3.2.0", "3.2.1", "3.2.2", "3.2.3", "3.2.4", "3.2.5", "3.2.6", "3.2.7",
     "3.3.0-preview1", "3.3.0-preview2", "3.3.0-preview3", "3.3.0-rc1", "3.3.0", "3.3.1", "3.3.2", "3.3.3", "3.3.4", "3.3.5", "3.3.6", "3.3.7",
     "3.4.0-preview1", "3.4.0-preview2", "3.4.0-rc1", "3.4.0", "3.4.1", "3.4.2",
-    "head", "debug", "asan"
+    "head", "debug", "asan", "3.4-asan"
   ],
   "jruby": [
     "9.1.17.0",