test/channelz: Don't try to dial non-dialable addresses

[twz123]

On some platforms, dialing 127.0.0.1:0 doesn't fail immediately but rather blocks until it times out. This leads to test failures because the leak detector identifies stray goroutines.

Even if the tests don't need the dial to succeed, create a random listener and use that as resolved address.

RELEASE NOTES: none

[codecov]

Codecov Report

❌ Patch coverage is 89.23077% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.28%. Comparing base (25dbb81) to head (e8e0327).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
clientconn.go	80.00%	5 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8782      +/-   ##
==========================================
- Coverage   83.29%   83.28%   -0.01%     
==========================================
  Files         414      414              
  Lines       32753    32793      +40     
==========================================
+ Hits        27280    27312      +32     
- Misses       4070     4080      +10     
+ Partials     1403     1401       -2     

Files with missing lines	Coverage Δ
balancer_wrapper.go	85.34% <100.00%> (+1.93%)	⬆️
internal/testutils/pipe_listener.go	84.61% <100.00%> (+0.83%)	⬆️
test/rawConnWrapper.go	66.10% <100.00%> (+0.28%)	⬆️
clientconn.go	90.16% <80.00%> (+0.18%)	⬆️

... and 23 files with indirect coverage changes

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[eshitachandwani]

Instead of failing unconditionally , would a better way be to create a net.Listener and and pass it's address like :

lis, err := net.Listen("tcp", "localhost:0")
if err != nil {
    t.Fatalf("Failed to listen: %v", err)
}
defer lis.Close()

And then pass the address as

	resolvedAddrs := []resolver.Address{{Addr: lis.Addr().String(), ServerName: "grpclb.server"}}

[twz123]

Instead of failing unconditionally , would a better way be to create a net.Listener and and pass it's address like :

lis, err := net.Listen("tcp", "localhost:0")
if err != nil {
    t.Fatalf("Failed to listen: %v", err)
}
defer lis.Close()

And then pass the address as

	resolvedAddrs := []resolver.Address{{Addr: lis.Addr().String(), ServerName: "grpclb.server"}}

Right. I've tried this, and, funnily enough, when I allow the tests to dial, I encounter leak detector errors due to #8655. However, if I merge #8666 into this PR, the leak detector errors disappear.

I'll mark this one as draft until #8655 has been sorted out.

[github-actions]

This PR is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.

[github-actions]

This PR is labeled as requiring an update from the reporter, and no update has been received after 6 days. If no update is provided in the next 7 days, this issue will be automatically closed.