tests: fixes for gating tests
    
    * plans/ci: setting "how: beakerlib" in execute step is deprecated.
      changed to "how: tmt" to comply with newer tmt versions.
      tmt versions.
    * ltrace with both --o and --c does not produce output to file:
      add malloc to the list of syscalls to check for tracing.
    * ltrace crashes when run on certain processes with --S option:
      make pgrep to exact match to avoid getting two PIDs, one from
      dbus-broker and other from dbus-broker-launch.
    * ltrace doesn't work on PIE-binaries:
      Added missing 32-bit dependencies.