Upgrade commons-lang to commons-lang3 and refactor commons-configuration usage

[krusche]

Summary

• Upgrade from commons-lang:2.x to commons-lang3:3.20.0
• Refactor code to remove direct dependency on commons-configuration Configuration interface
• Add explicit commons-lang3 dependency (previously pulled transitively)

Fixes #1603

Changes

Dependencies (build.gradle, eureka-client/build.gradle)

• Added commons-lang3:3.20.0 as explicit dependency
• Kept commons-configuration:1.10 (required at compile time by archaius-core:0.7.6)

Code changes

• PropertiesInstanceConfig.java: Refactored getMetadataMap() to use ConfigurationManager.getConfigInstance() directly instead of casting to Configuration interface
• DiscoveryClient.java: Updated import from org.apache.commons.lang.exception.ExceptionUtils to org.apache.commons.lang3.exception.ExceptionUtils
• RedirectingEurekaHttpClient.java: Same import update

Notes

• commons-configuration:1.10 cannot be fully removed because archaius-core:0.7.6 requires it at compile time (its API returns AbstractConfiguration types)
• Full migration to commons-configuration2 would require upgrading to archaius2, which is a larger breaking change affecting 24+ files
• The eureka-client-archaius2 module already exists as an alternative for users who want archaius2 support

Testing

• All modules compile successfully
• All tests pass (verified with Java 8 in Docker)
• No API changes for consumers