Filter datasource encryption master key from cluster settings GET API

[vamsimanohar]

Description

This PR is to disable master key reading from cluster settings API.

Before the change
GET localhost:9200/_cluster/settings?include_defaults=true

"plugins": {
            "ppl": {
                "enabled": "true"
            },
            "query": {
                "memory_limit": "85%",
                "metrics": {
                    "rolling_interval": "60",
                    "rolling_window": "3600"
                },
                "datasources": {
                    "encryption": {
                        "masterkey": "0000000000000000"
                    },
                    "uri": {
                        "allowhosts": ".*"
                    }
                },
                "size_limit": "200"
            },

After the change
GET localhost:9200/_cluster/settings?include_defaults=true

"plugins": {
            "ppl": {
                "enabled": "true"
            },
            "query": {
                "memory_limit": "85%",
                "metrics": {
                    "rolling_interval": "60",
                    "rolling_window": "3600"
                },
                "datasources": {
                    "uri": {
                        "allowhosts": ".*"
                    }
                },
                "size_limit": "200"
            }

Issues Resolved

[List any issues this PR will resolve]

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• 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.

[Yury-Fridlyand]

Can you add an IT? Thanks

[codecov]

Codecov Report

Merging #1825 (418b5e9) into main (a816a58) will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #1825   +/-   ##
=========================================
  Coverage     97.33%   97.33%           
  Complexity     4490     4490           
=========================================
  Files           394      394           
  Lines         11118    11119    +1     
  Branches        795      795           
=========================================
+ Hits          10822    10823    +1     
  Misses          289      289           
  Partials          7        7           

Flag	Coverage Δ
sql-engine	97.33% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...rch/sql/opensearch/setting/OpenSearchSettings.java	100.00% <ø> (ø)

... and 1 file with indirect coverage changes