[BUILD] auron-build.sh writes build info to the caller's directory and silently drops project.version #2459

Describe the bug

Running auron-build.sh from anywhere other than the project root fails in two quiet ways:

1. auron-build-info.properties gets written under the current directory instead of the project, so the build never picks it up and the resource is missing from the jar.
2. project.version is left out of the file, because the command that looks it up fails and the error is discarded.

Neither one stops the build. It runs to completion and produces a jar where AuronBuildInfo.VERSION is empty.

To Reproduce

Steps to reproduce the behavior:

1. mkdir -p /tmp/elsewhere && cd /tmp/elsewhere
2. bash /path/to/auron/auron-build.sh --release --sparkver 3.1 --scalaver 2.12
3. Look at the build configuration the script prints
4. Check /tmp/elsewhere/common/src/main/resources/auron-build-info.properties

[INFO] Build configuration (from 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]   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

project.version is missing from that list, and the file itself was created under /tmp/elsewhere rather than in the project.

Expected behavior

The build info file should land in the project regardless of where the script is invoked from, project.version should always be set, and a failure to resolve it should stop the build rather than produce a jar with no version in it.

Screenshots

N/A

Additional context

Three separate one-line causes, all on master:

• auron-build.sh:526 sets BUILD_INFO_FILE relative to the current directory rather than to the script.
• auron-build.sh:530 runs ./build/mvn directly instead of the MVN_CMD that was already resolved back at line 153.
• That same line sends stderr to /dev/null, and the write loop at line 565 only writes non-empty values, so the failure never shows up in the output or in the file.

Resolving the paths from BASH_SOURCE, reusing MVN_CMD, and failing when the version can't be resolved would cover all three.