Improve schema deletion by paging for large data

[zhoney]

implemented: #416

Change-Id: I61f11dfb6367acab9369b53af57c9114a11782c7

[codecov]

Codecov Report

Merging #417 into master will decrease coverage by 0.01%.
The diff coverage is 76.05%.

@@             Coverage Diff              @@
##             master     #417      +/-   ##
============================================
- Coverage     70.16%   70.15%   -0.02%     
- Complexity     3273     3280       +7     
============================================
  Files           208      208              
  Lines         16054    16081      +27     
  Branches       2301     2310       +9     
============================================
+ Hits          11264    11281      +17     
- Misses         3536     3549      +13     
+ Partials       1254     1251       -3

Impacted Files	Coverage Δ	Complexity Δ
...com/baidu/hugegraph/backend/page/IdHolderList.java	66.66% <ø> (ø)	9 <0> (ø)	⬇️
...aidu/hugegraph/backend/page/PageEntryIterator.java	83.33% <100%> (+1.28%)	17 <9> (+3)	⬆️
...du/hugegraph/backend/tx/GraphIndexTransaction.java	79.36% <100%> (-0.48%)	145 <0> (ø)
...gegraph/backend/store/scylladb/ScyllaDBTables.java	78.22% <100%> (ø)	13 <0> (ø)	⬇️
...n/java/com/baidu/hugegraph/config/CoreOptions.java	98.59% <100%> (ø)	2 <0> (ø)	⬇️
...m/baidu/hugegraph/backend/tx/GraphTransaction.java	82.12% <53.33%> (-0.8%)	208 <2> (+1)
.../java/com/baidu/hugegraph/backend/query/Query.java	69.91% <83.33%> (+1.39%)	49 <3> (+3)	⬆️
.../hugegraph/backend/store/BackendEntryIterator.java	66.66% <83.33%> (+2.08%)	14 <0> (ø)	⬇️
...va/com/baidu/hugegraph/backend/page/QueryList.java	78.78% <90.9%> (-3.32%)	16 <2> (-1)
...ain/java/com/baidu/hugegraph/task/TaskManager.java	60.86% <0%> (-4.35%)	10% <0%> (-1%)
... and 6 more

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