Tweak leak sanitizer suppressions for Cling, XrootD and TStreamerInfo with LCG97a

• Since the move to LCG 97a LHCb leak sanitiser builds have been swamped with errors like

==2164==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x7f1ba34ee333 in operator new(unsigned long) /build/gcc/build/contrib/gcc-9.2.0/src/gcc/9.2.0/libsanitizer/lsan/lsan_interceptors.cc:222
    #1 0x7f1b8956159b in cling::Interpreter::ShutDown() (/cvmfs/lhcb.cern.ch/lib/lcg/releases/LCG_97a/ROOT/v6.20.06/x86_64-centos7-gcc9-dbg/lib/libCling.so+0x6aa59b)

which appears to be a leak from ROOT's cling during shutdown. This MR adds a suppression for this.

Issue submitted at https://sft.its.cern.ch/jira/browse/ROOT-10959

• Some additional tweaks to the suppressions for Xrootd and TStreamerInfo are also required.

@clemenci @graven could the lhcb-sanitizers label be added for this please ?