Fix miniAOD validation for MET : 76X

[mmarionncern]

Same as #10019 for 76X

@davidlange6

[cmsbuild]

A new Pull Request was created by @mmarionncern for CMSSW_7_6_X.

Fix miniAOD validation for MET : 76X

It involves the following packages:

Configuration/StandardSequences
JetMETCorrections/Type1MET

@cmsbuild, @vadler, @franzoni, @davidlange6, @monttj can you please review it and eventually sign? Thanks.
@ghellwig, @TaiSakuma, @jdolen, @makortel, @GiacomoSguazzoni, @rappoccio, @rovere, @VinInn, @Martin-Grunewald, @ahinzmann, @nhanvtran, @schoef, @cerati, @mariadalfonso, @dgulhan this is something you requested to watch as well.
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