RANGER-5727: Upgrade OS to Ubuntu 26.04 LTS, comes with Python 3.14

[kumaab]

What changes were proposed in this pull request?

Upgrade the ranger-base Docker image from Ubuntu 22.04 (jammy) to Ubuntu 26.04 (resolute) to support the latest apache-ranger Python client, which requires Python ≥ 3.13.

• Switch base image to eclipse-temurin:${RANGER_BASE_JAVA_VERSION}-jdk-resolute (JDK 8 unchanged)
• Install apache-ranger into a dedicated venv at /opt/venv using system Python 3.14
• Fix PATH to include ${JAVA_HOME}/bin and /opt/venv/bin so java and python3 work as expected

How was this patch tested?

• Build base image: ./docker/build.sh (or docker build -f docker/Dockerfile -t apache/ranger-base:dev . from repo root)
• Verify Java: docker run --rm apache/ranger-base:dev java -version (JDK 8)
• Verify Python: docker run --rm apache/ranger-base:dev python3 --version (3.14+)
• Verify client: docker run --rm apache/ranger-base:dev python3 -c "from apache_ranger.client.ranger_client import RangerClient"
• CI builds ranger-base for jdk8/jdk11/jdk17 on amd64 and arm64

[adoroszlai]

LGTM

[kumaab]

• Verified instructions in https://github.com/apache/ranger-tools/blob/main/release/README.md are working for Ranger 2.9 release using the changes in this base image.
• Ranger UI is accessible.
• Following can be seen inside the container

ranger@ranger-admin:/$ python --version
Python 3.14.4
ranger@ranger-admin:/$ pip list
Package            Version
------------------ ---------
apache-ranger      0.0.13
certifi            2026.7.22
charset-normalizer 3.4.9
idna               3.18
pip                25.1.1
requests           2.34.2
StrEnum            0.4.15
urllib3            2.7.0

ranger@ranger-admin:/$ java -version
openjdk version "1.8.0_492"
OpenJDK Runtime Environment (Temurin)(build 1.8.0_492-b09)
OpenJDK 64-Bit Server VM (Temurin)(build 25.492-b09, mixed mode)

CC: @mneethiraj