[Backport 2.8] Separate config option to enable restapi: permissions (#2605)

[DarshitChanpura]

Backports #2605 to 2.8

Check List

• New functionality includes testing
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

Merging #2818 (3b854dd) into 2.8 (2ebcfa7) will decrease coverage by 0.11%.
The diff coverage is 53.33%.

@@             Coverage Diff              @@
##                2.8    #2818      +/-   ##
============================================
- Coverage     61.44%   61.34%   -0.11%     
+ Complexity     3376     3369       -7     
============================================
  Files           264      264              
  Lines         18631    18637       +6     
  Branches       3283     3285       +2     
============================================
- Hits          11447    11432      -15     
- Misses         5603     5618      +15     
- Partials       1581     1587       +6     

Impacted Files	Coverage Δ
...security/dlic/rest/api/SecuritySSLCertsAction.java	71.13% <ø> (-0.59%)	⬇️
...g/opensearch/security/support/ConfigConstants.java	94.44% <ø> (ø)
...dlic/rest/api/RestApiAdminPrivilegesEvaluator.java	75.75% <41.66%> (-2.58%)	⬇️
.../opensearch/security/OpenSearchSecurityPlugin.java	80.23% <100.00%> (+0.03%)	⬆️
...arch/security/dlic/rest/api/AbstractApiAction.java	75.96% <100.00%> (+0.09%)	⬆️

... and 6 files with indirect coverage changes