test: Fix provisioning tests by ignoring maybe-missing google-cloud-sdk

We're seeing intermittent provisioning failures with this message:

```
No apt package "google-cloud-sdk", but there is a snap with that name.
Try "snap install google-cloud-sdk"

E: Unable to locate package google-cloud-sdk
Error: Process completed with exit code 100.
```

I couldn't figure out why, but all we care about is that it's gone, so I'm
adding a wildcard. (It is also unlikely that there are any packages that we
*do* want that have that prefix.)

.github/workflows/provisioning-tests.yml

@@ -51,7 +51,11 @@ jobs:
           docker compose --version
 
       - name: free up disk space
-        run:  sudo apt remove --purge -y ghc-* azure-cli google-cloud-sdk hhvm llvm-* dotnet-* powershell mono-* php* ruby*
+        # google-cloud-sdk has an asterisk because as of 2023-09-27 it
+        # is sometimes not appearing in the Ubuntu package lists,
+        # causing this removal to fail. Using a wildcard allows the
+        # missing package to be ignored because it expands to nothing.
+        run:  sudo apt remove --purge -y ghc-* azure-cli google-cloud-sdk* hhvm llvm-* dotnet-* powershell mono-* php* ruby*
 
       - name: set up requirements
         run:  make requirements