tests: set the OPERATOR_NAMESPACE in the test suite

This allows one to run the a specific test using the ginkgo cli or by
using the vscode test decorators.

For example:
```
$ ginkgo -focus "ClientProfile Controller" -r
[1732083376] Controller Suite - 1/3 specs SS• SUCCESS! 5.797831s PASS
  Starting ceph-csi-operator suite
[1732083376] e2e suite - 0/1 specs S SUCCESS! 59.25µs PASS

Ginkgo ran 2 suites in 10.605577042s
Test Suite Passed
```

Signed-off-by: Raghavendra Talur <[email protected]>

internal/controller/suite_test.go

@@ -18,6 +18,7 @@ package controller
 
 import (
 	"fmt"
+	"os"
 	"path/filepath"
 	"runtime"
 	"testing"
@@ -66,6 +67,11 @@ var _ = BeforeSuite(func() {
 			fmt.Sprintf("1.29.0-%s-%s", runtime.GOOS, runtime.GOARCH)),
 	}
 
+	_, set := os.LookupEnv("OPERATOR_NAMESPACE")
+	if !set {
+		Expect(os.Setenv("OPERATOR_NAMESPACE", "ceph-csi-operator-system")).To(Succeed())
+	}
+
 	var err error
 	// cfg is defined in this file globally.
 	cfg, err = testEnv.Start()