Handle multiple directories in SSL_CERT_DIR env variable

[iiljkic]

Description

Currently, the SSL_CERT_DIR environment variable is treated as a single directory path. However, this variable often contains multiple paths separated by the OS path separator. See the OpenSSL manual:

If any directories are named on the command line, then those are processed in turn. If not, then the SSL_CERT_DIR environment variable is consulted; this should be a colon-separated list of directories, like the Unix PATH variable. If that is not set then the default directory (installation-specific but often /usr/local/ssl/certs) is processed.
Reference: https://docs.openssl.org/3.1/man1/openssl-rehash/#synopsis

This PR updates the certificate loading logic to support multiple directories, ensuring broader compatibility with enterprise and containerized environments.

Changes Proposed

• Split paths safely: The SSL_CERT_DIR string is now split using the OS-specific path separator (File.pathSeparator).
• Process independently: Each directory is processed individually to load the certificates.

Testing Done

• Verified that the code correctly parses multiple directories using OS-specific delimiters.
• Verified that the code still correctly processes single directory variable values.
• Verified that invalid or empty directory strings are gracefully ignored.
• Ran ./gradlew :api:spotlessApply, ./gradlew build, and ./gradlew runFunctionalTest and confirmed everything still green.

[iiljkic]

Reverted the renamings to keep the diff as small as possible

[iiljkic]

I removed the getDirectories() helper and inlined the path-splitting logic

Note: I assumed you meant to inline it inside getTrustManagerFromDir() rather than getTrustManagerFromFile()