PileUpMT: Fix placement of using declarations.

Don't put using declarations in the global namespace in headers.

This merge request affects 1 package:

• Control/PileUpMT

This merge request affects 2 files:

• Control/PileUpMT/src/PileUpMTAlg.cxx
• Control/PileUpMT/src/PileUpMTAlg.h

Adding @ssnyder as watcher

added Core main review-pending-level-1 labels

CI Result SUCCESS (hash f4dfb1bf)

	Athena
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 2641]

MR looks fine from L1 perspective, CI shows no problems - approving.

Cheers, Yuriy (L1)

removed review-pending-level-1 label

added review-approved label

merged

mentioned in commit df0c0023