fix: set max firewall name to 36

[NissesSenap]

This, to be able to have longer and unique names.
The firewall API supports 63 charters
Solves #1527

https://cloud.google.com/compute/docs/reference/rest/v1/firewalls

# The longest name with the extra chars added by the module
echo gke--intra-cluster-egress |wc -c
26
# the max ammount of char - the number of chars the module creates
expr 63 - 26
37
# I picked 36 since it looks better then 37 :)

[bharathkkb]

/gcbrun

[bharathkkb]

Thanks for the PR @NissesSenap

Looks like some of our tests may need updating

terraform-google-kubernetes-engine/test/integration/safer_cluster/safer_cluster_test.go

Lines 66 to 67 in d252579

	gcloud.Runf(t, "compute firewall-rules --project %s describe gke-%s-intra-cluster-egress", projectId, clusterName[:25])
	gcloud.Runf(t, "compute firewall-rules --project %s describe gke-%s-webhooks", projectId, clusterName[:25])

[NissesSenap]

@bharathkkb I updated the tests as you pointed out

[bharathkkb]

/gcbrun

[bharathkkb]

Looks like 36 is OOB since the test cluster name is smaller but I think we can just skip truncating since it's a static size from example.

 --- FAIL: TestSaferCluster (30.46s)
 panic: runtime error: slice bounds out of range [:36] with length 26 [recovered]
 	panic: runtime error: slice bounds out of range [:36] with length 26

[bharathkkb]

/gcbrun