Run UI test on Ubuntu 22.04 again.

Since 24.04 results in many (unpredictable) failures (see experiments
[here](#1040)),
we revert to 22.04 until we can practically use 24.04.

Author: toinehartman

.github/workflows/build.yaml

@@ -49,7 +49,7 @@ jobs:
   ui-test:
     strategy:
       matrix:
-        os: [ubicloud-standard-4, windows-latest, macos-latest]
+        os: [ubicloud-standard-4-ubuntu-2204, windows-latest, macos-latest]
       fail-fast: true
     env:
       CODE_VERSION: "1.90.2"