monitoring : adding migration tape backlog metrics to repo

monitoring/metrics/MigrationBacklogNb-CERNT3.metric

+# cernt3 migration backlog informations
+
+<metric>
+  name: MigrationBacklogNb-CERNT3
+  window: 60
+  unit: Nb of files and GB
+  category: CERNT3
+  conditions: DAEMON=="stagerd" and INSTANCE=="c2cernt3" and MSG=="waitTapeMigrationStats"
+  groupbykeys: TapePool
+  data: Adder(nbFiles)
+  handle_unordered: time_threshold
+  nbins: 1
+</metric>

monitoring/metrics/MigrationBacklogNb-PUBLIC.metric

+# migration backlog informations
+
+<metric>
+  name: MigrationBacklogNb-PUBLIC
+  window: 60
+  unit: Nb of files
+  category: Public
+  conditions: DAEMON=="stagerd" and INSTANCE=="c2public" and MSG=="waitTapeMigrationStats"
+  groupbykeys: TapePool
+  data: Adder(nbFiles)
+  handle_unordered: time_threshold
+  nbins: 1
+</metric>

monitoring/metrics/MigrationBacklogSize-CERNT3.metric

+# cernt3 migration backlog informations
+
+<metric>
+  name: MigrationBacklogSize-CERNT3
+  window: 60
+  unit: Nb of files and GB
+  category: CERNT3
+  conditions: DAEMON=="stagerd" and INSTANCE=="c2cernt3" and MSG=="waitTapeMigrationStats"
+  groupbykeys: TapePool
+  data: AdderGB(totalFileSize)
+  handle_unordered: time_threshold
+  nbins: 1
+</metric>

monitoring/metrics/MigrationBacklogSize-PUBLIC.metric

+# migration backlog informations
+
+<metric>
+  name: MigrationBacklogSize-PUBLIC
+  window: 60
+  unit: GB
+  category: Public
+  conditions: DAEMON=="stagerd" and INSTANCE=="c2public" and MSG=="waitTapeMigrationStats"
+  groupbykeys: TapePool
+  data: AdderGB(totalFileSize)
+  handle_unordered: time_threshold
+  nbins: 1
+</metric>

monitoring/metrics/MigrationBacklogStats-CERNT3.metric

+# cernt3 migration backlog informations
+
+<metric>
+  name: MigrationBacklogStats-CERNT3
+  window: 60
+  unit: Nb of files and GB
+  category: CERNT3
+  conditions: DAEMON=="stagerd" and INSTANCE=="c2cernt3" and MSG=="waitTapeMigrationStats"
+  groupbykeys: NONE
+  data: AdderGB(totalFileSize), Adder(nbFiles)
+  handle_unordered: time_threshold
+  nbins: 1
+</metric>

monitoring/metrics/MigrationBacklogStats-PUBLIC.metric

+# migration backlog informations
+
+<metric>
+  name: MigrationBacklogStats-PUBLIC
+  window: 60
+  unit: Nb of files and GB
+  category: Public
+  conditions: DAEMON=="stagerd" and INSTANCE=="c2public" and MSG=="waitTapeMigrationStats"
+  groupbykeys: NONE
+  data: AdderGB(totalFileSize), Adder(nbFiles)
+  handle_unordered: time_threshold
+  nbins: 1
+</metric>