Fix/zkname

[LaurenceLiZhixin]

What this PR does:
Change zkname from default to url.Location, which is more clear to define the zk client. The old way would let different directories with different zk location to have same zk client, which will caust bugs in 1.5 and 3.0 's multy-zone samples.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

Codecov Report

Merging #1263 (49f8c5e) into 1.5 (a10ff4d) will decrease coverage by 7.56%.
The diff coverage is 60.90%.

@@            Coverage Diff             @@
##              1.5    #1263      +/-   ##
==========================================
- Coverage   66.13%   58.57%   -7.57%     
==========================================
  Files         174      273      +99     
  Lines        9343    13269    +3926     
==========================================
+ Hits         6179     7772    +1593     
- Misses       2541     4536    +1995     
- Partials      623      961     +338     

Impacted Files	Coverage Δ
cluster/cluster_impl/available_cluster_invoker.go	66.66% <ø> (-6.67%)	⬇️
cluster/cluster_impl/broadcast_cluster_invoker.go	76.47% <ø> (-3.53%)	⬇️
cluster/cluster_impl/failfast_cluster_invoker.go	66.66% <ø> (-4.77%)	⬇️
cluster/cluster_impl/mock_cluster.go	0.00% <0.00%> (ø)
cluster/loadbalance/random.go	100.00% <ø> (ø)
cluster/router/healthcheck/factory.go	66.66% <0.00%> (ø)
common/extension/auth.go	0.00% <ø> (ø)
common/extension/cluster.go	0.00% <ø> (ø)
common/extension/cluster_interceptor.go	0.00% <0.00%> (ø)
common/extension/config_center.go	0.00% <ø> (ø)
... and 388 more

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