Upgrade Alerting to 2.0

[lezzago]

Issue #, if available:
#313 - OpenSearch 2.0 Upgrade
#325 - Remove JDK 8 support
#351 - Fix issue by upgrading to 2.0
#317 - Remove mapping type
#246 - Upgrade to Gradle 7
Description of changes:

• Build Alerting for OS 2.0
• Security integ test fails due to this issue

CheckList:
[X] Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov-commenter]

Codecov Report

Merging #357 (4fd1825) into main (120f7c4) will increase coverage by 0.15%.
The diff coverage is 16.66%.

@@             Coverage Diff              @@
##               main     #357      +/-   ##
============================================
+ Coverage     79.00%   79.16%   +0.15%     
  Complexity      268      268              
============================================
  Files           176      176              
  Lines          7288     7286       -2     
  Branches       1016     1016              
============================================
+ Hits           5758     5768      +10     
+ Misses         1004      993      -11     
+ Partials        526      525       -1     

Impacted Files	Coverage Δ
...rting/transport/TransportIndexDestinationAction.kt	62.09% <0.00%> (ø)
...ting/transport/TransportIndexEmailAccountAction.kt	63.90% <0.00%> (ø)
...erting/transport/TransportIndexEmailGroupAction.kt	59.80% <0.00%> (ø)
.../alerting/transport/TransportIndexMonitorAction.kt	62.44% <0.00%> (+0.29%)	⬆️
.../kotlin/org/opensearch/alerting/util/IndexUtils.kt	74.41% <0.00%> (ø)
...lin/org/opensearch/alerting/alerts/AlertIndices.kt	73.68% <100.00%> (+7.23%)	⬆️
...nsearch/alerting/core/model/ClusterMetricsInput.kt	95.36% <0.00%> (-0.04%)	⬇️

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