KYLIN-3414 Optimize the cleanup of project L2 cache

[GinaZhai]

No description provided.

[asfgit]

Can one of the admins verify this patch?

[shaofengshi]

LGTM

[coveralls]

Pull Request Test Coverage Report for Build 3352

• 1 of 12 (8.33%) changed or added relevant lines in 4 files are covered.
• 11 unchanged lines in 7 files lost coverage.
• Overall coverage decreased (-0.007%) to 24.638%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
core-metadata/src/main/java/org/apache/kylin/metadata/cachesync/Broadcaster.java	0	3	0.0%
core-metadata/src/main/java/org/apache/kylin/metadata/project/ProjectL2Cache.java	0	3	0.0%
core-metadata/src/main/java/org/apache/kylin/metadata/project/ProjectManager.java	0	5	0.0%

Files with Coverage Reduction	New Missed Lines	%
server-base/src/main/java/org/apache/kylin/rest/util/QueryRequestLimits.java	1	47.62%
core-metadata/src/main/java/org/apache/kylin/source/datagen/ColumnGenerator.java	1	81.08%
core-metadata/src/main/java/org/apache/kylin/metadata/project/ProjectManager.java	1	12.2%
core-metadata/src/main/java/org/apache/kylin/metadata/cachesync/Broadcaster.java	1	57.71%
core-dictionary/src/main/java/org/apache/kylin/dict/lookup/cache/RocksDBLookupTable.java	1	81.08%
core-metadata/src/main/java/org/apache/kylin/metadata/project/ProjectL2Cache.java	1	3.13%
core-cube/src/main/java/org/apache/kylin/cube/inmemcubing/MemDiskStore.java	5	77.81%

Totals
Change from base Build 3340:	-0.007%
Covered Lines:	15459
Relevant Lines:	62745

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💛 - Coveralls