[Backport 2.x]Fix build errors after refactoring of Strings class in core (#786)

[Hailong-am]

Backport 30e16d9 from #786

[codecov]

Codecov Report

Merging #845 (dba0f5f) into 2.x (344839a) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                2.x     #845      +/-   ##
============================================
- Coverage     75.72%   75.66%   -0.07%     
+ Complexity     2885     2881       -4     
============================================
  Files           366      366              
  Lines         16558    16558              
  Branches       2397     2397              
============================================
- Hits          12539    12529      -10     
- Misses         2640     2646       +6     
- Partials       1379     1383       +4     

Impacted Files	Coverage Δ
...nt/indexstatemanagement/model/destination/Chime.kt	55.55% <ø> (ø)
...statemanagement/model/destination/CustomWebhook.kt	68.57% <ø> (ø)
...nt/indexstatemanagement/model/destination/Slack.kt	77.77% <ø> (ø)
...statemanagement/resthandler/RestAddPolicyAction.kt	80.95% <ø> (ø)
...temanagement/resthandler/RestChangePolicyAction.kt	95.00% <ø> (ø)
...exstatemanagement/resthandler/RestExplainAction.kt	100.00% <ø> (ø)
...temanagement/resthandler/RestRemovePolicyAction.kt	100.00% <ø> (ø)
...t/resthandler/RestRetryFailedManagedIndexAction.kt	88.00% <ø> (ø)
...refreshanalyzer/RestRefreshSearchAnalyzerAction.kt	94.11% <ø> (ø)
...ment/rollup/resthandler/RestExplainRollupAction.kt	100.00% <ø> (ø)
... and 3 more

... and 12 files with indirect coverage changes

[Hailong-am]

security test failed due to OpenSearchSecurityPlugin is not latest

java.lang.NoClassDefFoundError: org/opensearch/core/common/io/stream/BaseStreamInput
»  	at org.opensearch.security.action.configupdate.ConfigUpdateAction.<init>(ConfigUpdateAction.java:37)
»  	at org.opensearch.security.action.configupdate.ConfigUpdateAction.<clinit>(ConfigUpdateAction.java:33)
»  	at org.opensearch.security.OpenSearchSecurityPlugin.getActions(OpenSearchSecurityPlugin.java:570)
»  	at org.opensearch.action.ActionModule.lambda$setupActions$3(ActionModule.java:714)
»  	at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:27