HPCC-10318 ConfigMgr - default environment.xml fails validation

  - Reset deprecated build tag in default environment.xml to '_'

Signed-off-by: Gleb Aronsky <gleb.aronsky@lexisnexis.com>
Merge pull request #5075 from garonsky/HPCC-10318_default_env_fails_validaton_due_to_build

HPCC-10318 ConfigMgr - default environment.xml fails validation

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>