fix: Add check that we're able to run the e2e.GoBuild method in `TestPrimary_stateStore_unmanaged_separatePlan` (#38190)

This change should hopefully address E2E failures that are happening on main. It's hard to test that as the failures are platform specific and neither my laptop nor the runner for tests on PRs matches the failing platforms.

internal/command/e2etest/pluggable_state_store_test.go

@@ -35,6 +35,15 @@ import (
 // As well as ensuring that the state store can be initialised ok, this tests that
 // the state store's details can be stored in the plan file despite the fact it's reattached.
 func TestPrimary_stateStore_unmanaged_separatePlan(t *testing.T) {
+	if !canRunGoBuild {
+		// We're running in a separate-build-then-run context, so we can't
+		// currently execute this test which depends on being able to build
+		// new executable at runtime.
+		//
+		// (See the comment on canRunGoBuild's declaration for more information.)
+		t.Skip("can't run without building a new provider executable")
+	}
+
 	fixturePath := filepath.Join("testdata", "full-workflow-with-state-store-fs")
 
 	t.Setenv(e2e.TestExperimentFlag, "true")