Honour the CCDB time machine for the mu(bc) distribution

The mu(bc) lookup in CollisionContextTool uses its own CCDBManagerInstance,
which -- unlike BasicCCDBManager -- never picks up the time-machine constraint
from ALICEO2_CCDB_CONDITION_NOT_AFTER. FT0/Calib/EventsPerBc was therefore
resolved against the present even when a time machine was requested, quietly
switching the sampler and changing the collision context at an unchanged seed.
Bunch filling and mean vertex, which go through BasicCCDBManager, were pinned
correctly.

Now carry the constraint over explicitly. See O2-7093.

Author: sawenzel

Steer/src/CollisionContextTool.cxx

@@ -440,6 +440,10 @@ int main(int argc, char* argv[])
             // for now construct a specific CCDBManager for this query
             o2::ccdb::CCDBManagerInstance ccdb_inst(ccdb_info.server + std::string(":") + ccdb_info.port);
             ccdb_inst.setFatalWhenNull(false);
+            // this is a private instance, so it does not inherit the time-machine
+            // constraint that BasicCCDBManager picks up from the environment;
+            // carry it over explicitly (a 0 here means "unconstrained" anyway)
+            ccdb_inst.setCreatedNotAfter(o2::ccdb::BasicCCDBManager::instance().getCreatedNotAfter());
             auto local_hist = ccdb_inst.getForTimeStamp<TH1F>(ccdb_info.fullPath, options.timestamp);
             if (local_hist) {
               // case in which CCDB object contains directly a ROOT histogram