Remove hardcoded provider

[terryquigleysas]

Description

Category (Refactoring)
Remove call to add the BouncyCastleProvider in OpenSearchSecurityPlugin.java and any associated code.
This may have several benefits:

• Removal of unnecessary code
• Helps towards potential support of FIPS-compatible Bouncy Castle provider
• Removes another SecurityManager referenc

Issues Resolved

Resolves #4583

Testing

Bulk Integration Test Github action

Run latest 3.x Core and OpenSearch Security plugin. Smoke tests (Indexing, searching, user creation, role creation, security admin script calls) run against both:

• JDK 17 - local
• JDK 21 - shipped with OS

Check List

• New functionality includes testing
• New functionality has been documented
• New Roles/Permissions have a corresponding security dashboards plugin PR
• API changes companion pull request created
• Commits are signed per the DCO using --signoff

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