#157 feat: upgrade to UBI 10

Re-attempting upgrade to UBI 10 to resolve #149 with fixes from https://github.com/fluent/fluent-bit/pull/11111

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Summary by cubic

Upgrade Docker base images to Red Hat UBI 10.2 for builder and runtime to pick up security updates and align with Fluent Bit upstream, resolving #149. Prefer system zstd and improve container testing, with checks to keep Dockerfile distro metadata in sync.

• New Features

  • Prefer system zstd (install zstd in runtime; build with -DFLB_PREFER_SYSTEM_LIB_ZSTD=On)
  • Add helper to build/test local images in KIND and a container test for the systemd input

• Bug Fixes

  • Fix ldconfig setup for libgit2 and libssh2, correct distro metadata to ubi/10.2, and add Dockerfile checks in scripts/update-version.sh to keep TELEMETRY_FORGE_AGENT_DISTRO in sync for UBI/Debian
  • Fix test script env var handling and skip pulls when testing local images