unflake TestAgentAntiEntropy_EnableTagOverride

#### Overview of the Issue

https://github.com/hashicorp/consul/blob/59f14628010f24ae5b1480072fd7600b3606b8f7/agent/local/state_test.go#L491

Test runs completed fairly quickly with a result of `DONE 1000 tests, 57 failures in 1066.944s`

The rough local success rate is 94.3%.

Test errors look like this clause but repeated a few hundred times. The large sample I took got a bit borked up because of this, the output was massive, even with only 57 failures.

```
assertions.go:260:
Error Trace: state_test.go:618
retry.go:130
asm_amd64.s:1337
Error: Not equal:
expected: &structs.NodeService{Kind:"", ID:"svc_id1", Service:"svc1", Tags:[]string{"tag1_mod"}, Address:"", TaggedAddresses:map[string]structs.ServiceAddress(nil), Meta:map[string]string(nil), Port:6100, Weights:(*structs.Weights)(0xc00066ff60), EnableTagOverride:true, ProxyDestination:"", Proxy:structs.ConnectProxyConfig{DestinationServiceName:"", DestinationServiceID:"", LocalServiceAddress:"", LocalServicePort:0, Config:map[string]interface {}(nil), Upstreams:structs.Upstreams(nil), MeshGateway:structs.MeshGatewayConfig{Mode:""}}, Connect:structs.ServiceConnect{Native:false, Proxy:(*structs.ServiceDefinitionConnectProxy)(nil), SidecarService:(*structs.ServiceDefinition)(nil)}, LocallyRegisteredAsSidecar:false, RaftIndex:structs.RaftIndex{CreateIndex:0x0, ModifyIndex:0x0}}
actual : &structs.NodeService{Kind:"", ID:"svc_id1", Service:"svc1", Tags:[]string{"tag1"}, Address:"", TaggedAddresses:map[string]structs.ServiceAddress(nil), Meta:map[string]string(nil), Port:6100, Weights:(*structs.Weights)(0xc00136ce30), EnableTagOverride:true, ProxyDestination:"", Proxy:structs.ConnectProxyConfig{DestinationServiceName:"", DestinationServiceID:"", LocalServiceAddress:"", LocalServicePort:0, Config:map[string]interface {}(nil), Upstreams:structs.Upstreams(nil), MeshGateway:structs.MeshGatewayConfig{Mode:""}}, Connect:structs.ServiceConnect{Native:false, Proxy:(*structs.ServiceDefinitionConnectProxy)(nil), SidecarService:(*structs.ServiceDefinition)(nil)}, LocallyRegisteredAsSidecar:false, RaftIndex:structs.RaftIndex{CreateIndex:0x0, ModifyIndex:0x0}}

Diff:
--- Expected
+++ Actual
@@ -5,3 +5,3 @@
Tags: ([]string) (len=1) {
- (string) (len=8) "tag1_mod"
+ (string) (len=4) "tag1"
},
```

#### Reproduction Steps

Run the test a bunch
```
env GOMAXPROCS=8 gotestsum --format short-verbose --jsonfile TestAgentAntiEntropy_EnableTagOverride.json -- ./agent/local -run TestAgentAntiEntropy_EnableTagOverride -count 1000 -timeout 0
```

### Operating system and Environment details

CircleCI, macOS 10.14.6

### Log Fragments
The local log output of this was pretty gnarly and hard to paste in (lots of repetitive assertions failures, dozens of MB), but the errors I was able to observe follow the form of the CI errors. The json output of gotestsum is about 83MB so I'm going to hold off on pasting it here, I think we have everything we need from the CI output.

CI:
- https://circleci.com/gh/hashicorp/consul/56692#tests/containers/7
- https://circleci.com/gh/hashicorp/consul/94595#tests/containers/7