dev: `make test` target fails with overriden k8gb env vars

[somaritane]

make test (unit test) build target fails when k8gb env vars are set in the shell
or .env file before running the target:

❯ EDGE_DNS_SERVER=8.8.8.8 make test
...
                                Diff:
                                --- Expected
                                +++ Actual
                                @@ -14,3 +14,3 @@
                                  },
                                - fallbackEdgeDNSServerName: (string) "",
                                + fallbackEdgeDNSServerName: (string) (len=7) "8.8.8.8",
                                  fallbackEdgeDNSServerPort: (int) 53,
                Test:           TestResolveConfigWithNegativeReconcileRequeueSecondsKey
...

❯ touch .env; make test
...
                                Diff:
                                --- Expected
                                +++ Actual
                                @@ -14,3 +14,3 @@
                                  },
                                - fallbackEdgeDNSServerName: (string) "",
                                + fallbackEdgeDNSServerName: (string) (len=7) "1.1.1.1",
                                  fallbackEdgeDNSServerPort: (int) 53,
                Test:           TestResolveConfigWithNegativeReconcileRequeueSecondsKey
...

❯ echo "EDGE_DNS_SERVER=8.8.8.8" > .env; make test
...
                                Diff:
                                --- Expected
                                +++ Actual
                                @@ -14,3 +14,3 @@
                                  },
                                - fallbackEdgeDNSServerName: (string) "",
                                + fallbackEdgeDNSServerName: (string) (len=7) "8.8.8.8",
                                  fallbackEdgeDNSServerPort: (int) 53,
                Test:           TestResolveConfigWithZeroReconcileRequeueSecondsKey
...

IMHO unit testing environment should be isolated and not dependant on externally set variables.