Block delete default cluster

[zouyx]

修复

• 演示环境删除某项目default集群，回到界面报错 Ref：演示环境删除某项目default集群，回到界面报错 #1571

[codecov-io]

Codecov Report

Merging #1586 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master    #1586      +/-   ##
============================================
+ Coverage     48.62%   48.66%   +0.03%     
- Complexity     1899     1901       +2     
============================================
  Files           393      393              
  Lines         11494    11496       +2     
  Branches       1194     1195       +1     
============================================
+ Hits           5589     5594       +5     
+ Misses         5477     5473       -4     
- Partials        428      429       +1

Impacted Files	Coverage Δ	Complexity Δ
...llo/adminservice/controller/ClusterController.java	30.76% <100%> (+18.26%)	4 <0> (+2)	⬆️

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[coveralls]

Coverage increased (+0.04%) to 52.392% when pulling ee136b7 on zouyx:master into 2dbb811 on ctripcorp:master.

[nobodyiam]

Thanks, will take a look soon.

[nobodyiam]

ok