[Backport 2.x] Improve serialization speeds (#2802)

[cwperks]

Backport #2802 to 2.x

[codecov]

Codecov Report

Merging #3444 (4aaba72) into 2.x (a2daf9f) will increase coverage by 0.45%.
Report is 14 commits behind head on 2.x.
The diff coverage is 80.00%.

@@             Coverage Diff              @@
##                2.x    #3444      +/-   ##
============================================
+ Coverage     64.11%   64.56%   +0.45%     
- Complexity     3367     3507     +140     
============================================
  Files           256      260       +4     
  Lines         19515    19714     +199     
  Branches       3297     3306       +9     
============================================
+ Hits          12512    12729     +217     
+ Misses         5360     5353       -7     
+ Partials       1643     1632      -11     

Files	Coverage Δ
.../main/java/com/amazon/dlic/auth/ldap/LdapUser.java	89.28% <100.00%> (+3.57%)	⬆️
...earch/security/auditlog/impl/AbstractAuditLog.java	76.53% <100.00%> (+0.10%)	⬆️
...ava/org/opensearch/security/auth/UserInjector.java	90.66% <100.00%> (+0.66%)	⬆️
...org/opensearch/security/filter/SecurityFilter.java	66.66% <100.00%> (+0.80%)	⬆️
...urity/ssl/transport/SecuritySSLRequestHandler.java	62.22% <100.00%> (+3.13%)	⬆️
.../org/opensearch/security/support/Base64Helper.java	90.90% <100.00%> (+23.63%)	⬆️
...g/opensearch/security/support/ConfigConstants.java	95.23% <100.00%> (+0.23%)	⬆️
.../org/opensearch/security/support/HeaderHelper.java	62.50% <100.00%> (+2.50%)	⬆️
...rch/security/transport/SecurityRequestHandler.java	55.03% <100.00%> (+0.30%)	⬆️
...c/main/java/org/opensearch/security/user/User.java	71.95% <100.00%> (+15.70%)	⬆️
... and 7 more

... and 20 files with indirect coverage changes