DPL: avoid expensive find_if for check of AVAILABLE_MANAGED_SHM metric when sending metrics

[ehellbar]

CPU usage tests on my laptop

O2_DPL_DEPLOYMENT_MODE=Local o2-qc-run-producer -b --monitoring-backend infologger://debug --message-rate 1000 --min-size 10 --max-size 10
before: dummy-sink at 41%, producer-0 at 18%
with this PR: dummy-sink at 18%, producer-0 at 13%

O2_DPL_DEPLOYMENT_MODE=OnlineECS o2-qc-run-producer -b --monitoring-backend infologger://debug --message-rate 1000 --min-size 10 --max-size 10
before: dummy-sink at 53%, producer-0 at 20%
with this PR: dummy-sink at 35%, producer-0 at 18%

[github-actions]

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[alibuild]

Error while checking build/O2/fullCI_slc9 for 507ce9a at 2025-04-02 21:11:

## sw/BUILD/O2Physics-latest/log
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:
Error in cling::AutoLoadingVisitor::InsertIntoAutoLoadingState:


## sw/BUILD/O2-full-system-test-latest/log
Detected critical problem in logfile digi.log
digi.log:[22951:internal-dpl-ccdb-backend]: [21:10:55][ERROR] Exception while running: Fatal error. Rethrowing.
digi.log-[22951:internal-dpl-ccdb-backend]: [21:10:55][FATAL] Unhandled o2::framework::runtime_error reached the top of main of o2-sim-digitizer-workflow, device shutting down. Reason: Fatal error
[22951:internal-dpl-ccdb-backend]: [21:10:53][ERROR] CCDBDownloader CURL transfer error - Timeout was reached
[22951:internal-dpl-ccdb-backend]: [21:10:53][ERROR] CcdbDownloader finished transfer http://alice-ccdb.cern.ch/CTP/Calib/OrbitReset for 1550600800000 (agent_id: alimetal04.cern.ch-1743621043-N7HpVr) with http code: 0
[22951:internal-dpl-ccdb-backend]: [21:10:53][ERROR] File CTP/Calib/OrbitReset could not be retrieved. No more hosts to try.
[22951:internal-dpl-ccdb-backend]: [21:10:53][FATAL] Unable to find CCDB object CTP/Calib/OrbitReset/1550600800000
[22951:internal-dpl-ccdb-backend]: [21:10:55][ERROR] Exception while running: Fatal error. Rethrowing.
[22951:internal-dpl-ccdb-backend]: [21:10:55][FATAL] Unhandled o2::framework::runtime_error reached the top of main of o2-sim-digitizer-workflow, device shutting down. Reason: Fatal error
[ERROR] Workflow crashed - PID 22951 (internal-dpl-ccdb-backend) did not exit correctly however it's not clear why. Exit code forced to 128.


## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
grep: error-log.txt: binary file matches
++ GRERR=1
++ [[ 1 == 0 ]]
++ mkdir -p /sw/INSTALLROOT/15937eb851264b8104acb0f9e0a501d619a9f107/slc9_x86-64/o2checkcode/1.0-local67/etc/modulefiles
++ cat
--

Full log here.