Quick updated to Jenkins (health check) launch script (#3033)

# Description

This is a quick hotfix for small discrepancy in the Jenkins health check
launch script that runs in cron:

`gh -> "${GH}"`

# Type of change
- [x] Bug fix (fixes something broken)
- [ ] New feature (adds functionality)
- [ ] Maintenance (code refactor, clean-up, new CI test, etc.)

# Change characteristics
<!-- Choose YES or NO from each of the following and delete the other
-->
- Is this a breaking change (a change in existing functionality)? NO
- Does this change require a documentation update? NO
- Does this change require an update to any of the following submodules?
NO

# How is this tested

Ran in cron on Hercules and Orion

Co-authored-by: tmcguinness <[email protected]>

ci/scripts/utils/launch_java_agent.sh

@@ -106,7 +106,7 @@ export GH="${HOME}/bin/gh"
 [[ -f "${GH}" ]] || echo "gh is not installed in ${HOME}/bin"
 ${GH} --version
 
-check_mark=$(gh auth status -t 2>&1 | grep "Token:" | awk '{print $1}') || true
+check_mark=$("${GH}" auth status -t 2>&1 | grep "Token:" | awk '{print $1}') || true
 if [[ "${check_mark}" != "✓" ]]; then
   echo "gh not authenticating with emcbot token"
   exit 1