Fix TestAccComputeRoute_hopInstance now that we store the self link

[danawillow]

$ make testacc TEST=./google TESTARGS='-run=TestAccComputeRoute_hopInstance'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./google -v -run=TestAccComputeRoute_hopInstance -timeout 120m
=== RUN   TestAccComputeRoute_hopInstance
--- PASS: TestAccComputeRoute_hopInstance (71.60s)
PASS
ok  	github.com/terraform-providers/terraform-provider-google/google	71.755s

If you want I can add the actual project value here, to me it didn't seem like it would really make a difference.

[ghost]

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