[AURON #2459] Resolve build info paths relative to auron-build.sh

[ShreyeshArangath]

What changes were proposed in this pull request?

Fixes #2459.

auron-build.sh resolved both the build info file and the Maven used to look up project.version relative to the caller's working directory. Run from anywhere other than the project root, it wrote auron-build-info.properties outside the project so the build never picked it up, and left project.version out of the file entirely because the lookup failed into /dev/null and empty values are skipped by the writing loop.

Three changes:

• Resolve SCRIPT_DIR from BASH_SOURCE and use it for BUILD_INFO_FILE, so the file always lands in the project.
• Use the already resolved MVN_CMD instead of a hardcoded ./build/mvn.
• Pass -f "$SCRIPT_DIR/pom.xml" so Maven reads the project pom, and fail with the captured Maven output when the version cannot be resolved.

The -f part is worth calling out. Without it, help:evaluate run from another directory does not fail; Maven falls back to its synthetic standalone pom and reports version 1, so the jar gets a plausible but wrong version. Pinning the pom and validating the result covers that.

How was this patch tested?

Manually, on Spark 3.1 / Scala 2.12.

Before, from a directory outside the project, project.version is missing and the file is written to the wrong place:

$ cd /tmp/elsewhere && bash /path/to/auron/auron-build.sh --release --sparkver 3.1 --scalaver 2.12
[INFO] Build configuration (from common/src/main/resources/auron-build-info.properties):
[INFO]   spark.version : 3.1
[INFO]   scala.version : 2.12
[INFO]   build.timestamp : 2026-08-08T23:32:59Z
auron-build.sh: line 611: /tmp/elsewhere/build/mvn: No such file or directory

After, from the same directory:

[INFO] Build configuration (from /path/to/auron/common/src/main/resources/auron-build-info.properties):
[INFO]   spark.version : 3.1
[INFO]   rust.version : 1.97.1
[INFO]   java.version : 17.0.19
[INFO]   project.version : 9.0.0-SNAPSHOT
[INFO]   scala.version : 2.12
[INFO]   build.timestamp : 2026-08-10T05:07:19Z

Also checked:

• Running from the project root is unchanged.
• Nothing is written into the caller's directory any more.
• With an unresolvable Maven the script now exits 1 and prints the Maven output, instead of continuing and producing a jar with no version.