llama-swap: fix build on Darwin

llama-swap has added a new test TestProcess_ReverseProxyPanicIsHandled
that isn't covered by the existing skippedTests list, and which fails in
a similar way to those tests on the x86_64 build.

Meanwhile, the aarch64 build is now failing on the same tests that
previously only had problems on x86_64. (At least on Hydra - don't have
an Apple Silicon machine to test locally on.)

This adds the new test to skippedTests, and enables the skippedTests
list for both Darwin platforms, rather than just x86_64.

Fixes #483423.

pkgs/by-name/ll/llama-swap/package.nix

@@ -81,8 +81,8 @@ buildGoModule (finalAttrs: {
 
   checkFlags =
     let
-      skippedTests = lib.optionals (stdenv.isDarwin && stdenv.isx86_64) [
-        # Fail only on x86_64-darwin intermittently
+      skippedTests = lib.optionals (stdenv.isDarwin) [
+        # Fail only on *-darwin intermittently
         # https://github.com/mostlygeek/llama-swap/issues/320
         "TestProcess_AutomaticallyStartsUpstream"
         "TestProcess_WaitOnMultipleStarts"
@@ -98,6 +98,7 @@ buildGoModule (finalAttrs: {
         "TestProcess_ForceStopWithKill"
         "TestProcess_StopCmd"
         "TestProcess_EnvironmentSetCorrectly"
+        "TestProcess_ReverseProxyPanicIsHandled"
       ];
     in
     [ "-skip=^${builtins.concatStringsSep "$|^" skippedTests}$" ];