bump version to 2.1.0

[nobodyiam]

What's the purpose of this PR

bump apollo version to 2.1.0

Brief changelog

• bump apollo and apollo-java version to 2.1.0
• change the releases.enabled to false for snapshot's repository as it only contains the snapshot artifacts

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• Read the Contributing Guide before making this pull request.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit tests to verify the code.
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• Update the CHANGES log.

[codecov]

Codecov Report

Merging #4715 (ecd9dee) into master (f28a01a) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4715      +/-   ##
============================================
- Coverage     47.25%   47.22%   -0.03%     
  Complexity     1661     1661              
============================================
  Files           349      349              
  Lines         10691    10691              
  Branches       1062     1062              
============================================
- Hits           5052     5049       -3     
- Misses         5333     5334       +1     
- Partials        306      308       +2     

Impacted Files	Coverage Δ
...mework/apollo/portal/component/PortalSettings.java	65.62% <0.00%> (-4.69%)	⬇️
...ervice/service/ReleaseMessageServiceWithCache.java	85.88% <0.00%> (-1.18%)	⬇️
...o/openapi/filter/ConsumerAuthenticationFilter.java	100.00% <0.00%> (+5.88%)	⬆️

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